We extend the noncommutative (NC) standard model to incorporate singlet particles as cold dark matter. In the NC space-time, the singlet particles can be coupled to the $U(1)$ gauge field in the adjoint representation. We study the relic density of the singlet particles due to the NC induced interaction. Demanding either the singlet fermion or the singlet scalar to serve as cold dark matter and the NC induced interactions to be relevant to the dark matter production, we obtain the corresponding relations between the NC scale and the dark matter masses, which are consistent with some existing bounds.

We present numerical evidence for the existence of stationary spinning generalizations for the static sphaleron in the Weinberg-Salam theory. Our results suggest that, for any value of the mixing angle ${\theta }_{\mathrm{W}}$ and for any Higgs mass, the spinning sphalerons comprise a family labeled by their angular momentum $J$. For ${\theta }_{\mathrm{W}}\ne 0$ they possess an electric charge $Q=eJ$, where $e$ is the electron charge. Inside they contain a monopole-antimonopole pair and a spinning loop of electric current, and for large $J$, a Regge-type behavior. It is likely that these sphalerons mediate the topological transitions in sectors with $J\ne 0$, thus enlarging the number of transition channels. Their action decreases with $J$, which may considerably affect the total transition rate.

We study the Hamiltonian formulation of the general first order action of general relativity compatible with local Lorentz invariance and background independence. The most general simplectic structure (compatible with diffeomorphism invariance and local Lorentz transformations) is obtained by adding to the Holst action the Pontriagin, Euler, and Nieh-Yan invariants with independent coupling constants. We perform a detailed canonical analysis of this general formulation (in the time gauge) exploring the structure of the phase space in terms of connection variables. We explain the relationship of these topological terms and the effect of large $SU(2)$ gauge transformations in quantum theories of gravity defined in terms of the Ashtekar-Barbero connection.

The full set of equations governing the structure and the evolution of self-gravitating spherically symmetric dissipative fluids with anisotropic stresses is written down in terms of five scalar quantities obtained from the orthogonal splitting of the Riemann tensor, in the context of general relativity. It is shown that these scalars are directly related to fundamental properties of the fluid distribution, such as energy density, energy density inhomogeneity, local anisotropy of pressure, dissipative flux, and the active gravitational mass. It is also shown that in the static case, all possible solutions to Einstein equations may be expressed explicitly through these scalars. Some solutions are exhibited to illustrate this point.

The role of chirality is discussed in unifying the anomaly and the tunneling formalisms for deriving the Hawking effect. Using the chirality condition and starting from the familiar form of the trace anomaly, the chiral (gravitational) anomaly, manifested as a nonconservation of the stress tensor, near the horizon of a black hole, is derived. Solution of this equation yields the stress tensor whose asymptotic infinity limit gives the Hawking flux. Finally, use of the same chirality condition in the tunneling formalism gives the Hawking temperature that is compatible with the flux obtained by anomaly method.

We give here a new third post-Newtonian (3PN) spin-spin contribution (in the PN parameter $\epsilon$) to the accumulated orbital phase of a compact binary, arising from the spin-orbit precessional motion of the spins. In the equal mass case, this contribution vanishes, but Laser Interferometer Space Antenna (LISA) sources of merging supermassive binary black holes have typically a mass ratio of 1:10. For such nonequal masses, this 3PN correction is periodic in time, with a period approximately ${\epsilon }^{-1}$ times larger than the period of gravitational waves. We derive a renormalized and simpler expression of the spin-spin coefficient at 2PN, as an average over the time scale of this period of the combined 2PN and 3PN contribution. We also find that for LISA sources the quadrupole-monopole contribution to the phase dominates over the spin-spin contribution, while the self-spin contribution is negligible even for the dominant spin. Finally, we define a renormalized total spin coefficient $\overline{\sigma }$ to be employed in the search for gravitational waves emitted by LISA sources.

We present a study of scattering of massless planar scalar waves by a charged nonrotating black hole. Partial wave methods are applied to compute scattering and absorption cross sections, for a range of incident wavelengths. We compare our numerical results with semiclassical approximations from a geodesic analysis, and find excellent agreement. The glory in the backward direction is studied, and its properties are shown to be related to the properties of the photon orbit. The effects of the black hole charge upon scattering and absorption are examined in detail. As the charge of the black hole is increased, we find that the absorption cross section decreases, and the angular width of the interference fringes of the scattering cross section at large angles increases. In particular, the glory spot in the backward direction becomes wider. We interpret these effects under the light of our geodesic analysis.

We obtain the general static, spherically symmetric solution for the Einstein-Maxwell-dilaton system in four dimensions with a phantom coupling for the dilaton and/or the Maxwell field. This leads to new classes of black hole solutions, with single or multiple horizons. Using the geodesic equations, we analyze the corresponding Penrose diagrams revealing, in some cases, new causal structures.

The cosmic microwave background (CMB) is a rich source of cosmological information. Thanks to the simplicity and linearity of the theory of cosmological perturbations, observations of the CMB’s polarization and temperature anisotropy can reveal the parameters that describe the contents, structure, and evolution of the cosmos. Temperature anisotropy is necessary but not sufficient to fully mine the CMB of its cosmological information as it is plagued with various parameter degeneracies. Fortunately, CMB polarization breaks many of these degeneracies and adds new information and increased precision. Of particular interest is the CMB’s $B$-mode polarization, which provides a handle on several cosmological parameters most notably the tensor-to-scalar ratio $r$ and is sensitive to parameters that govern the growth of large-scale structure and evolution of the gravitational potential. These imprint CMB temperature anisotropy and cause $E$-to-$B$-mode polarization conversion via gravitational lensing. However, both primordial gravitational-wave- and secondary lensing-induced $B$-mode signals are very weak and therefore prone to various foregrounds and systematics. In this work we use Fisher-matrix-based estimations and apply, for the first time, Monte Carlo Markov Chain simulations to determine the effect of beam systematics on the inferred cosmological parameters from five upcoming experiments: PLANCK, POLARBEAR, SPIDER, $\mathrm{QUIET}+\mathrm{CLOVER}$, and CMBPOL. We consider beam systematics that couple the beam substructure to the gradient of temperature anisotropy and polarization (differential beamwidth, pointing offsets and ellipticity) and beam systematics due to differential beam normalization (differential gain) and orientation (beam rotation) of the polarization-sensitive axes (the latter two effects are insensitive to the beam substructure). We determine allowable levels of beam systematics for given tolerances on the induced parameter errors and check for possible biases in the inferred parameters concomitant with potential increases in the statistical uncertainty. All our results are scaled to the “worst case scenario.” In this case, and for our tolerance levels the beam rotation should not exceed the few-degree to subdegree level, typical ellipticity is required to be 1%, the differential gain allowed level is a few parts in ${10}^3$ to ${10}^4$, differential beam width upper limits are of the subpercent level, and differential pointing should not exceed the few- to sub-arc sec level.

Polarimetry of the cosmic microwave background represents one of the possible diagnostics aimed at testing large-scale magnetism at the epoch of the photon decoupling. The propagation of electromagnetic disturbances in a magnetized plasma leads naturally to a B-mode polarization whose angular power spectrum is hereby computed both analytically and numerically. Combined analyses of all the publicly available data on the B-mode polarization are presented, for the first time, in the light of the magnetized $\Lambda \mathrm{CDM}$ scenario. Novel constraints on preequality magnetism are also derived in view of the current and expected sensitivities to the B-mode polarization.

We extend the constrained minimal supersymmetric model (CMSSM) by adding a right-handed neutrino superfield ($\nu \mathrm{CMSSM}$) which decouples close to the GUT scale. We study the effects of a right-handed neutrino on the low energy spectrum and focus on the predictions for dark matter properties. We pay particular attention to the realization of the light (left-handed) sneutrino which can be the next-to-lightest supersymmetric particle (NLSP) with either the neutralino or gravitino as the lightest supersymmetric particle (LSP). Notably, for the case of a neutralino LSP with a sneutrino NLSP, there are new “sneutrino coannihilation regions” which yield the desired thermal neutralino relic density determined by WMAP.

The gluon collision process that creates a heavy-quark-antiquark pair with small relative momentum and large transverse momentum predicts at leading-order in the QCD coupling constant that the transverse polarization of the pair should increase with its transverse momentum. Measurements at the Fermilab Tevatron of the polarization of charmonium and bottomonium states with respect to a particular spin-quantization axis are inconsistent with this prediction. However the predicted rate of approach to complete transverse polarization depends on the choice of spin-quantization axis. We introduce axes that maximize and minimize the transverse polarization from the leading-order gluon collision process. They are determined by the direction of the jet that provides most of the balancing transverse momentum.

In the covariant light-front quark model, we investigate the form factors of $B_c$ decays into $D$, $D^{*}$, $D_s$, $D_s^{*}$, ${\eta }_c$, $J/\psi$, $B$, $B^{*}$, $B_s$, and $B_s^{*}$ mesons. The form factors in the spacelike region are directly evaluated. To extrapolate the form factors to the physical region, we fit the form factors by adopting a suitable three-parameter form. At the maximally recoiling point, $b\to u$, $d$, and $s$ transition form factors are smaller than $b\to c$ and $c\to d$, $s$ form factors, while the $b\to u$, $d$, $s$, and $c$ form factors at the zero-recoiling point are close to each other. In the fitting procedure, we find that parameters in $A_2^{B_c{B}^{*}}$ and $A_2^{B_c{B}_s^{*}}$ strongly depend on decay constants of $B^{*}$ and $B_s^{*}$ mesons. Fortunately, semileptonic and nonleptonic $B_c$ decays are not sensitive to these two form factors. We also investigate branching fractions, polarizations of the semileptonic $B_c$ decays. $B_c\to ({\eta }_c,J/\psi )l\nu$ and $B_c\to (B_s,B_s^{*})l\nu$ decays have much larger branching fractions than $B_c\to (D,D^{*},B,B^{*})l\nu$. For the three kinds of $B_c\to Vl\nu$ decays, longitudinal contributions are comparable with the transverse contributions. These predictions will be tested on the ongoing and forthcoming hadron colliders.

We reevaluate electron-positron pair production from electromagnetic interactions of muons in transit through materials. Our approach, through the use of structure functions for inelastic and elastic scattering and including hadronic recoil, make the formalism useful for tau pair production at high energies. Our results for electron-positron pairs agree well with prior evaluations. Tau pair production, however, has significant contributions from inelastic scattering in addition to the usual coherent scattering with the nucleus and scattering with atomic electrons.

We study the Sudakov form factor for a spontaneously broken gauge theory using a (new) $\Delta$-regulator. To be well defined, the effective theory requires zero-bin subtractions for the collinear sectors. The zero-bin subtractions depend on the gauge boson mass $M$ and are not scaleless. They have both finite and $1/ϵ$ contributions and are needed to give the correct anomalous dimension and low-scale matching contributions. We also demonstrate the necessity of zero-bin subtractions for soft-collinear factorization. We find that after zero-bin subtractions the form factor is the sum of the collinear contributions minus a soft mass-mode contribution, in agreement with a previous result of Idilbi and Mehen in QCD. This appears to conflict with the method-of-regions approach, where one gets the sum of contributions from different regions.

We present a measurement of the $t\overline{t}$ production cross section in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using events containing a high transverse momentum electron or muon, three or more jets, and missing transverse energy. Events consistent with $t\overline{t}$ decay are found by identifying jets containing candidate heavy-flavor semileptonic decays to muons. The measurement uses a CDF run II data sample corresponding to $2{\mathrm{fb}}^{-1}$ of integrated luminosity. Based on 248 candidate events with three or more jets and an expected background of $79.5\pm 5.3$ events, we measure a production cross section of $9.1\pm 1.6\mathrm{pb}$.

We study the charmless decays $B\to \Lambda \overline{\Lambda }h$, where $h$ stands for ${\pi }^{+}$, $K^{+}$, $K^0$,$K^{*+}$, or $K^{*0}$, using a $605{\mathrm{fb}}^{-1}$ data sample collected at the ${\rm Y}(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^{+}{e}^{-}$ collider. We observe $B^0\to \Lambda \overline{\Lambda }{K}^0$ and $B^0\to \Lambda \overline{\Lambda }{K}^{*0}$ with branching fractions of $({4.76}_{-0.68}^{+0.84}(\mathrm{stat})\pm 0.61(\mathrm{syst}))\times {10}^{-6}$ and $({2.46}_{-0.72}^{+0.87}\pm 0.34)\times {10}^{-6}$, respectively. The significances of these signals in the threshold-mass enhanced mass region, $M_{\Lambda \overline{\Lambda }}<2.85\mathrm{GeV}/c^2$, are $12.4\sigma$ and $9.3\sigma$, respectively. We also update the branching fraction $\mathcal{B}(B^{+}\to \Lambda \overline{\Lambda }{K}^{+})=({3.38}_{-0.36}^{+0.41}\pm 0.41)\times {10}^{-6}$ with better accuracy, and report the following measurement or 90% confidence level upper limit in the threshold-mass-enhanced region: $\mathcal{B}(B^{+}\to \Lambda \overline{\Lambda }{K}^{*+})=({2.19}_{-0.88}^{+1.13}\pm 0.33)\times {10}^{-6}$ with $3.7\sigma$ significance; $\mathcal{B}(B^{+}\to \Lambda \overline{\Lambda }{\pi }^{+})<0.94\times {10}^{-6}$. A related search for $B^0\to \Lambda \overline{\Lambda }{\overline{D}}^0$ yields a branching fraction $\mathcal{B}(B^0\to \Lambda \overline{\Lambda }{\overline{D}}^0)=({1.05}_{-0.44}^{+0.57}\pm 0.14)\times {10}^{-5}$. This may be compared with the large, $\sim {10}^{-4}$, branching fraction observed for $B^0\to p\overline{p}{\overline{D}}^0$. The $M_{\Lambda \overline{\Lambda }}$ enhancements near threshold and related angular distributions for the observed modes are also reported.

We present measurements of $B$ meson decays to the final states $\omega K^{*}$, $\omega \rho$, and $\omega f_0$, where $K^{*}$ indicates a spin 0, 1, or 2 strange meson. The data sample corresponds to $465\times {10}^6$ $B\overline{B}$ pairs collected with the BABAR detector at the PEP-II $e^{+}{e}^{-}$ collider at SLAC. $B$ meson decays involving vector-scalar, vector-vector, and vector-tensor final states are analyzed; the latter two shed new light on the polarization of these final states. We measure the branching fractions for nine of these decays; five are observed for the first time. For most decays we also measure the charge asymmetry and, where relevant, the longitudinal polarization $f_L$.

We study transitions between ${\rm Y}$ states with the emission of charged pions using $604.6{\mathrm{fb}}^{-1}$ of data collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The measured product branching fraction is $\mathcal{B}({\rm Y}(4S)\to {\rm Y}(1S){\pi }^{+}{\pi }^{-})\times \mathcal{B}({\rm Y}(1S)\to {\mu }^{+}{\mu }^{-})=(2.11\pm 0.30(\mathrm{stat})\pm 0.14(\mathrm{sys}))\times {10}^{-6}$ and the partial decay width is $\Gamma ({\rm Y}(4S)\to {\rm Y}(1S){\pi }^{+}{\pi }^{-})=(1.75\pm 0.25(\mathrm{stat})\pm 0.24(\mathrm{sys}))\mathrm{keV}$.

We discuss the derivation of dissipative Bjorken hydrodynamics from a Schwarzschild black hole in asymptotically AdS spacetime of arbitrary dimension in the limit of large longitudinal proper time $\tau$. Using an appropriate slicing near the boundary, we calculate the Schwarzschild metric to next-to-next-to-leading order in the large $\tau$ expansion, as well as the dual stress-energy tensor on the boundary via holographic renormalization. At next-to-next-to-leading order, it is necessary to perturb the Schwarzschild metric in order to maintain boost invariance. The perturbation has a power-law time dependence and leads to the same value of the ratio of viscosity to entropy density, $1/(4\pi )$, as in the case of sinusoidal perturbations. Our results are in agreement with known time-dependent asymptotic solutions of the Einstein equations in five dimensions.