Two recently proposed techniques, involving the measurement of the cosmic parallax and redshift drift, provide novel ways of directly probing (over a time span of several years) the background metric of the universe and therefore shed light on the dark-energy conundrum. The former makes use of upcoming high-precision astrometry measurements to either observe or put tight constraints on cosmological anisotropy for off-center observers, while the latter employs high-precision spectroscopy to give an independent test of the present acceleration of the universe. In this paper, we show that both methods can break the degeneracy between Lemaître-Tolman-Bondi void models and more traditional dark-energy theories. Using the near-future observational missions Gaia and CODEX we show that this distinction might be made with high confidence levels in the course of a decade.

McVittie’s spacetime is a spherically symmetric solution to Einstein’s equation with an energy-momentum tensor of a perfect fluid. It describes the external field of a single quasi-isolated object with a vanishing electric charge and angular momentum in an environment that asymptotically tends to a Friedmann-Lemaître-Robertson-Walker universe. We critically discuss some recently proposed generalizations of this solution, in which radial matter accretion as well as heat currents are allowed. We clarify the hitherto unexplained constraints between these two generalizing aspects as being due to a geometric property, here called “spatial Ricci-isotropy,” which forces solutions covered by the McVittie ansatz to be rather special. We also clarify other aspects of these solutions, like whether they include geometries which are in the same conformal equivalence class as the exterior Schwarzschild solution, which leads us to contradict some of the statements in the recent literature.

We show numerically that quarks develop an electric dipole moment in the direction of a sufficiently intense magnetic field due to local fluctuations of topological charge. This anomalous $CP$-odd effect is a spin analogue of the chiral magnetic effect in QCD.

${\mathrm{QCD}}_{\mathrm{AS}}$, a variant of large $N_c$ QCD in which quarks transform under the color two-index antisymmetric representation, reduces to standard QCD at $N_c=3$ and provides an alternative to the usual large $N_c$ extrapolation that uses fundamental representation quarks. Previous strong plausibility arguments assert that the ${\mathrm{QCD}}_{\mathrm{AS}}$ baryon mass scales as $N_c^2$; however, the complicated combinatoric problem associated with quarks carrying two color indices impeded a complete demonstration. We develop a diagrammatic technique to solve this problem. The key ingredient is the introduction of an effective multigluon vertex: a “traffic circle” or roundabout diagram. We show that arbitrarily complicated diagrams can be reduced to simple ones with the same leading $N_c$ scaling using this device, and that the leading contribution to baryon mass does, in fact, scale as $N_c^2$.

We analyze the rare semileptonic $B_c\to D_{s0}^{*}{l}^{+}{l}^{-}$, ($l=e$, $\mu$, $\tau$) and $B_c\to D_{s0}^{*}\nu \overline{\nu }$ decays in the framework of the three-point QCD sum rules. $D_{s0}^{*}$ is a scalar meson with total spin 0 and even parity. Taking into account the gluon condensate contributions as the important correction of the nonperturbative parts of the correlation function and the large effects of Coulombic corrections, the relevant form factors of these transitions have been calculated. The branching fractions and longitudinal lepton polarization asymmetry are also investigated.

Imagine discovering a new fourth family of leptons at the Large Hadron Collider (LHC) but no signs of an associated fourth family of quarks. What would that imply? An intriguing possibility is that the new fermions needed to compensate for the new leptons gauge anomalies simultaneously address the big hierarchy problem of the standard model. A natural way to accomplish such a scenario is to have the Higgs itself be a composite of these new fermions. This is the setup we are going to investigate in this paper using as a template minimal walking technicolor. We analyze a general heavy neutrino mass structure with and without mixing with the standard model families. We also analyze the LHC potential to observe the fourth lepton family in tandem with the new composite Higgs dynamics. We finally introduce a model uniting the fourth lepton family and the technifermion sector at higher energies.

Using a frequentist analysis of experimental constraints within two versions of the minimal supersymmetric extension of the standard model, we derive the predictions for the top quark mass, $m_t$, and the $W$ boson mass, $M_W$. We find that the supersymmetric predictions for both $m_t$ and $M_W$, obtained by incorporating all the relevant experimental information and state-of-the-art theoretical predictions, are highly compatible with the experimental values with small remaining uncertainties, yielding an improvement compared to the case of the standard model.

We study the nonforward Compton scattering, in particular, the deeply virtual Compton scattering from AdS/CFT. We first calculate the contributions from the $s$-channel and $u$-channel supergravity diagrams as well as the four-point interaction diagram which correspond to the Compton scatterings on a dilaton target in CFT. Furthermore, we study the Compton scattering on a dilatino target. Assuming that protons can be identified as supergravity modes of the dilatino, we compare the calculated deeply virtual Compton scattering cross section to the low-energy experimental data from the H1 and ZEUS collaborations and find good agreement. We also discuss the $t$-channel graviton exchange contribution and show that it should be dominant in the high-energy limit.

We present a high-statistics calculation of nucleon electromagnetic form factors in $N_f=2+1$ lattice QCD using domain wall quarks on fine lattices, to attain a new level of precision in systematic and statistical errors. Our calculations use ${32}^3\times 64$ lattices with lattice spacing $a=0.084\mathrm{fm}$ for pion masses of 297, 355, and 403 MeV, and we perform an overdetermined analysis using on the order of 3600 to 7000 measurements to calculate nucleon electric and magnetic form factors up to $Q^2\approx 1.05{\mathrm{GeV}}^2$. Results are shown to be consistent with those obtained using valence domain wall quarks with improved staggered sea quarks, and using coarse domain wall lattices. We determine the isovector Dirac radius $r_1^v$, Pauli radius $r_2^v$ and anomalous magnetic moment ${\kappa }_v$. We also determine connected contributions to the corresponding isoscalar observables. We extrapolate these observables to the physical pion mass using two different formulations of two-flavor chiral effective field theory at one loop: the heavy baryon small scale expansion and covariant baryon chiral perturbation theory. The isovector results and the connected contributions to the isoscalar results are compared with experiment, and the need for calculations at smaller pion masses is discussed.

The pion-mass dependence of hyperon electromagnetic properties is determined using two-flavor heavy baryon chiral perturbation theory. Specifically we compute chiral corrections to the charge radii, magnetic moments, and magnetic radii of the spin one-half hyperons, as well as the charge radii, magnetic moments, magnetic radii, electric quadrupole moments, and quadrupole radii of the spin three-half hyperons. Results for the nucleon and delta are also included. Efficacy of the two-flavor theory is investigated by analyzing the role played by virtual kaons. For the electromagnetic properties of spin one-half hyperons, kaon loop contributions are shown to be well described by terms analytic in the pion mass squared. Similarly kaon contributions to the magnetic moments of spin three-half hyperons are well described in the two-flavor theory. The remaining electromagnetic properties of spin three-half resonances can be described in two-flavor chiral perturbation theory, however, this description fails just beyond the physical pion mass. For the case of experimentally known hyperon magnetic moments and charge radii, we demonstrate that chiral corrections are under reasonable control, in contrast to the behavior of these observables in the three-flavor chiral expansion. The formulas we derive are ideal for performing the pion-mass extrapolation of lattice QCD data obtained at the physical strange quark mass.

We report results of a new global next-to-leading order fit of parton distribution functions in which cuts on $W$ and $Q$ are relaxed, thereby including more data at high values of $x$. Effects of target mass corrections, higher twist contributions, and nuclear corrections for deuterium data are significant in the large-$x$ region. The leading twist parton distributions are found to be stable to target mass correction model variations as long as higher twist contributions are also included. The behavior of the $d$ quark as $x\to 1$ is particularly sensitive to the deuterium corrections, and using realistic nuclear smearing models the $d$-quark distribution at large $x$ is found to be softer than in previous fits performed with more restrictive cuts.

In nonrelativistic quantum chromodynamics (NRQCD), we study the next-to-leading order (NLO) QCD radiative correction to the color-octet $J/\psi$ inclusive production at $B$ factories. Compared with the leading-order (LO) result, the NLO QCD corrections are found to enhance the short-distance coefficients in the color-octet $J/\psi$ production $e^{+}{e}^{-}\to c\overline{c}({}^{1}S_0^{(8)}\mathrm{\text{or}}{}^{3}P_J^{(8)})g$ (with $J=0$, 1, 2) by a factor of about 1.9. Moreover, the peak at the end point in the $J/\psi$ energy distribution predicted at LO can be smeared by the NLO corrections, but the major color-octet contribution still comes from the large energy region of $J/\psi$. By fitting the latest data of $\sigma (e^{+}{e}^{-}\to J/\psi +X_{\mathrm{non}\mathrm{\text{−}}c\overline{c}})$ observed by Belle, we find that the values of color-octet matrix elements are much smaller than expected earlier by using the naive velocity scaling rules or extracted from fitting experimental data with LO calculations. As the most stringent constraint by setting the color-singlet contribution to be zero in $e^{+}{e}^{-}\to J/\psi +X_{\mathrm{non}\mathrm{\text{−}}c\overline{c}}$, we get an upper limit of the color-octet matrix element, $⟨0|{\mathcal{O}}^{J/\psi }[{}^{1}S_0^{(8)}]|0⟩+4.0⟨0|{\mathcal{O}}^{J/\psi }[{}^{3}P_0^{(8)}]|0⟩/m_c^2<(2.0\pm 0.6)\times {10}^{-2}{\mathrm{GeV}}^3$ at NLO in ${\alpha }_s$.

It is shown that the electric dipole moment of the $\tau$ lepton several orders of magnitude larger than predicted by the standard model can be generated from mixings in models with vectorlike mutiplets. The electric dipole moment (EDM) of the $\tau$ lepton arises from loops involving the exchange of the $W$, the charginos, the neutralinos, the sleptons, the mirror leptons, and the mirror sleptons. The EDM of the Dirac $\tau$ neutrino is also computed from loops involving the exchange of the $W$, the charginos, the mirror leptons, and the mirror sleptons. A numerical analysis is presented, and it is shown that the EDMs of the $\tau$ lepton and the $\tau$ neutrino which lie just a couple of orders of magnitude below the sensitivity of the current experiment can be achieved. Thus the predictions of the model are testable in an improved experiment on the EDM of the $\tau$ and the $\tau$ neutrino.

Domain wall structure which may form in theories with spontaneously broken parity is generically in conflict with standard cosmology. It has been argued that Planck scale suppressed effects can be sufficient for removing such domain walls. We study this possibility for three specific evolution scenarios for the domain walls, with evolution during a radiation dominated era, during a matter dominated era, and that accompanied by weak inflation. We determine the operators permitted by the supergravity formalism and find that the field content introduced to achieve desired spontaneous parity breaking makes possible Planck scale suppressed terms which can potentially remove the domain walls safely. However, the parity breaking scale, equivalently the Majorana mass scale $M_R$ of the right-handed neutrino, does get constrained in some of the cases, notably for the matter dominated evolution case which would be generic to string theory inspired models, giving rise to moduli fields. One left-right symmetric model with only triplets and bidoublets is found to be more constrained than another admitting a gauge singlet.

We show that the five-dimensional Maxwell theory with the Chern-Simons term is tachyonic in the presence of a constant electric field. When coupled to gravity, a sufficiently large Chern-Simons coupling causes instability of the Reissner-Nordström black holes in anti-de Sitter space. The instability happens only at nonvanishing momenta, suggesting a spatially modulated phase in the holographically dual quantum field theory in ($3+1$) dimensions, with spontaneous current generation in a helical configuration. The three-charge extremal black hole in the type IIB superstring theory on ${\mathrm{AdS}}_5\times S^5$ barely satisfies the stability condition.

We study physical properties and global structures of a time-dependent, spherically symmetric solution obtained via the dimensional reduction of intersecting M-branes. We find that the spacetime describes a maximally charged black hole which asymptotically tends to the Friedmann-Lemaître-Robertson-Walker universe filled by a stiff matter. The metric solves the field equations of the Einstein-Maxwell-dilaton system, in which four Abelian gauge fields couple to the dilation with different coupling constants. The spacetime satisfies the dominant energy condition and is characterized by two parameters, $Q$ and $\tau$, related to the Maxwell charge and the relative ratio of black-hole horizon radii, respectively. In spite of the nontrivial time dependence of the metric, it turns out that the black-hole event horizon is a Killing horizon. This unexpected symmetry may be ascribed to the fact that the 11-dimensional brane configurations are supersymmetric in the static limit. Finally, combining with laws of the trapping horizon, we discuss the thermodynamic properties of the black hole. It is shown that the horizon possesses a nonvanishing temperature, contrary to the extremal Reissner-Nordström solution.

Recently a new four-dimensional nonrelativistic renormalizable theory of gravity was proposed by Hořava. In this paper we have found different near horizon geometries in Hořava gravity. We find the rotating solutions in a special range of parameters of the theory. This range allows us to include up to six derivative terms in the equations of motion. We have found our solutions as perturbed solutions over spherical symmetric background with small rotating parameter.

The Hamiltonian formulation of the Holst action in the presence of a massless fermion field with a nonminimal Lagrangian is performed without any restriction on the local Lorentz frame. It is outlined that the phase-space structure does not resemble that of a background-independent Lorentz gauge theory, as some additional constraints are present. Proper phase-space coordinates are introduced, such that SU(2) connections can be defined, and the vanishing of conjugate momenta to boost variables is predicted. Finally, it is demonstrated that for a particular value of the nonminimal parameter, the kinematics coincides with that of a background-independent SU(2) gauge theory, and the Immirzi parameter becomes the coupling constant of such an interaction between fermions and the gravitational field.

We present a method for calculating solutions and corresponding central charges for backgrounds with ${\mathrm{AdS}}_3$ and $S^k$ factors in ${\alpha }^{\prime }$-exact fashion from the full tree-level low-energy effective action of heterotic string theory. Three examples are explicitly presented: ${\mathrm{AdS}}_3\times S^3\times T^4$, ${\mathrm{AdS}}_3\times S^2\times S^1\times T^4$, and ${\mathrm{AdS}}_3\times S^3\times S^3\times S^1$. Crucial property which enabled our analysis is vanishing of the Riemann tensor calculated from connection with “$\sigma$-model torsion.” We show the following: (i) Chern-Simons terms are the only source of ${\alpha }^{\prime }$ corrections not only in BPS, but also in non-BPS cases, suggesting a possible extension of general method of Kraus and Larsen, (ii) our results are in agreement with some conjectures on the form of the part of tree-level Lagrangian not connected to a mixed Chern-Simons term by supersymmetry (and present in all supersymmetric string theories), (iii) new ${\alpha }^{\prime }$-exact result for central charges in ${\mathrm{AdS}}_3\times S^3\times S^3\times S^1$ geometry. As a tool we used our generalization of Sen’s $\mathcal{E}$-function formalism to ${\mathrm{AdS}}_p$ with $p>2$, and paid special attention to proper definition of asymptotic charges.

In this work we investigate the gravitational lensing effect in the strong field region around dilaton black holes in an anti–de Sitter space. We also analyze the dependence of the radius of the photon sphere and deflection angle on dilaton coupling and the cosmological constant in this black hole spacetime. Finally the values of minimum impact parameter, the separation between the first and the other images, as well as the ratio between the flux of the first image and the flux coming from all the other images are determined to characterize some possible distinct signatures of such black holes.