Unitarity implies that the evaporation of microscopic quasiclassical black holes cannot be universal in different particle species. This creates a puzzle, since it conflicts with the thermal nature of quasiclassical black holes, according to which all of the species should see the same horizon and be produced with the same Hawking temperatures. We resolve this puzzle by showing that for the microscopic black holes, on top of the usual quantum evaporation time, there is a new time scale which characterizes a purely classical process during which the black hole loses the ability to differentiate among the species and becomes democratic. We demonstrate this phenomenon in a well-understood framework of large extra dimensions, with a number of parallel branes. An initially nondemocratic black hole is the one localized on one of the branes, with its high-dimensional Schwarzschild radius being much shorter than the interbrane distance. Such a black hole seemingly cannot evaporate into the species localized on the other branes that are beyond its reach. We demonstrate that in reality the system evolves classically in time, in such a way that the black hole accretes the neighboring branes. The end result is a completely democratic static configuration, in which all of the branes share the same black hole and all of the species are produced with the same Hawking temperature. Thus, just like their macroscopic counterparts, the microscopic black holes are universal bridges to the hidden sector physics.

Making use of the fact that the optical geometry near a static nondegenerate Killing horizon is asymptotically hyperbolic, we investigate some universal features of black-hole horizons. Applying the Gauss-Bonnet theorem allows us to establish some general properties of gravitational lensing, valid for all black holes. Hyperbolic geometry allows us to find rates for the loss of scalar, vector, and fermionic “hair” as objects fall quasistatically towards the horizon, extending previous results for Schwarzschild to all static Killing horizons. In the process we find the Liénard-Wiechert potential for hyperbolic space and calculate the force between electrons mediated by neutrinos, extending the flat space result of Feinberg and Sucher. We further demonstrate how these techniques allow us to derive the exact Copson-Linet potential due to a point charge in a Schwarzschild background in a simple fashion.

We show that the 511 keV gamma ray excess observed by INTEGRAL/SPI can be more robustly explained by exciting dark matter (DM) at the center of the galaxy, if there is a peculiar spectrum of DM states ${\chi }_0$, ${\chi }_1$, and ${\chi }_2$, with masses $M_0\sim 500\mathrm{GeV}$, $M_1\lesssim M_0+2m_e$, and $M_2=M_1+\delta M\gtrsim M_0+2m_e$. The small mass splitting $\delta M$ should be $\lesssim 100\mathrm{keV}$. In addition, we require at least two new gauge bosons (preferably three), with masses $\sim 100\mathrm{MeV}$. With this spectrum, ${\chi }_1$ is stable but can be excited to ${\chi }_2$ by low-velocity DM scatterings near the Galactic center, which are Sommerfeld-enhanced by two of the 100 MeV gauge boson exchanges. The excited state ${\chi }_2$ decays to ${\chi }_0$ and nonrelativistic $e^{+}{e}^{-}$, mediated by the third gauge boson, which mixes with the photon and $Z$. Although such a small 100 keV splitting has been independently proposed for explaining the DAMA annual modulation through the inelastic DM mechanism, the need for stability of ${\chi }_1$ (and hence sequestering it from the standard model) implies that our scenario cannot account for the DAMA signal. It can, however, address the PAMELA/ATIC positron excess via DM annihilation in the galaxy, and it offers the possibility of a sharper feature in the ATIC spectrum relative to previously proposed models. The data are consistent with three new gauge bosons, whose couplings fit naturally into a broken SU(2) gauge theory where the DM is a triplet of the SU(2). We propose a simple model in which the SU(2) is broken by new Higgs triplet and 5-plet vacuum expectation values, giving rise to the right spectrum of DM and mixing of one of the new gauge bosons with the photon and $Z$ boson. A coupling of the DM to a heavy $Z^{\prime }$ may also be necessary to get the right relic density and PAMELA/ATIC signals.

We present a dark matter extension of the minimal supersymmetric standard model to give the recent trend of the high energy positron spectrum of the PAMELA/HEAT experiments. If the trend is caused indeed by dark matter, the minimal supersymmetric standard model needs to be extended. Here, we minimally extend the minimal supersymmetric standard model with one more dark matter component $N$ together with a heavy lepton $E$ and introduce the coupling $e_R{E}_R^c{N}_R$. This coupling naturally appears in the flipped SU(5) grand unification models. We also present the needed parameter ranges of these additional particles.

Some analyses of recent cosmic microwave background (CMB) data have provided hints that there are deviations from Gaussianity in the WMAP CMB temperature fluctuations. Given the far-reaching consequences of such a non-Gaussianity for our understanding of the physics of the early universe, it is important to employ alternative indicators in order to determine whether the reported non-Gaussianity is of cosmological origin, and/or extract further information that may be helpful for identifying its causes. We propose two new non-Gaussianity indicators, based on skewness and kurtosis of large-angle patches of CMB maps, which provide a measure of departure from Gaussianity on large angular scales. A distinctive feature of these indicators is that they provide sky maps of non-Gaussianity of the CMB temperature data, thus allowing a possible additional window into their origins. Using these indicators, we find no significant deviation from Gaussianity in the three and five-year WMAP Internal Linear Combination (ILC) map with KQ75 mask, while the ILC unmasked map exhibits deviation from Gaussianity, quantifying therefore the WMAP team recommendation to employ the new mask KQ75 for tests of Gaussianity. We also use our indicators to test for Gaussianity the single frequency foreground unremoved WMAP three and five-year maps, and show that the K and Ka maps exhibit a clear indication of deviation from Gaussianity even with the KQ75 mask. We show that our findings are robust with respect to the details of the method.

Detection of a gravitational-wave stochastic background via ground or space-based gravitational-wave detectors requires the cross correlation of the response of two or more independent detectors. The cross correlation involves a frequency-dependent factor—the so-called overlap reduction function or Hellings-Downs curve—that depends on the relative geometry of each detector pair, i.e., the detector separations and the relative orientation of their antenna patterns (beams). An incorrect formulation of this geometrical factor has appeared in the literature, leading to incorrect conclusions regarding the sensitivity of proposed detectors to a stochastic gravitational-wave background. To rectify these errors and as a reference for future work we provide here a complete, first-principles derivation of the overlap reduction function and assess the nature of the errors associated with the use of the incorrect expression that has appeared in the literature. We describe the behavior of the overlap reduction function in different limiting regimes, and show how the difference between the correct and incorrect expressions can be understood physically.

In models where the breaking of lepton number is spontaneous a massless Goldstone boson, the Majoron ($J$), appears. We calculate the theoretically allowed range for the branching ratios of Majoron-emitting charged lepton decays, such as $\mathrm{Br}(\mu \to eJ)$ and $\mathrm{Br}(\mu \to eJ\gamma )$, in a supersymmetric model with spontaneous breaking of $R$-parity. $\mathrm{Br}(\mu \to eJ)$ is maximal in the same region of parameter space for which the lightest neutralino decays mainly invisibly. A measurement of $\mathrm{Br}(\mu \to eJ)$ thus potentially provides information on $R$-parity violation complementary to accelerator searches. We also briefly discuss existing bounds and prospects for future improvements on the Majoron coupling to charged leptons.

We explore the possibility that weakly interacting dark matter can form bound states—WIMPonium. Such states are expected in a wide class of models of particle dark matter, including some limits of the minimal supersymmetric standard model. We examine the conditions under which we expect bound states to occur and use analogues of nonrelativistic QCD applied to heavy quarkonia to provide estimates for their properties, including couplings to the standard model. We further find that it may be possible to produce WIMPonium at the LHC and explore the properties of the WIMP that can be inferred from measurements of the WIMPonium states.

We calculate the form factor $f_{+}(q^2)$ for $B$-meson semileptonic decay in unquenched lattice QCD with $2+1$ flavors of light sea quarks. We use Asqtad-improved staggered light quarks and a Fermilab bottom quark on gauge configurations generated by the MILC Collaboration. We simulate with several light-quark masses and at two lattice spacings, and extrapolate to the physical quark mass and continuum limit using heavy-light meson staggered chiral perturbation theory. We then fit the lattice result for $f_{+}(q^2)$ simultaneously with that measured by the BABAR experiment using a parameterization of the form-factor shape in $q^2$, which relies only on analyticity and unitarity in order to determine the Cabibbo-Kobayashi-Maskawa matrix element $|V_{\mathrm{ub}}|$. This approach reduces the total uncertainty in $|V_{\mathrm{ub}}|$ by combining the lattice and experimental information in an optimal, model-independent manner. We find a value of $|V_{\mathrm{ub}}|\times {10}^3=3.38\pm 0.36$.

The ground-state energy of a collection of $n$ pions and $m$ kaons with short range interactions is calculated for a volume with finite spatial extent $L$ and periodic boundary conditions. This calculation is accomplished to order $L^{-6}$ in the large volume expansion. With this result one can extract the various two- and three-body interactions between pions and kaons from lattice QCD data.

Recent developments in models with warped extra dimensions have opened new possibilities for vectorlike quark studies at hadron colliders. These new vectorlike quarks can mix sizably with light standard model quarks without violating low energy constraints. We perform a model-independent analysis to determine the Tevatron reach in the search for new quarks. We find that the Tevatron has great potential to observe such quarks via their electroweak single production due to their mixing with valence quarks. With $4(8){\mathrm{fb}}^{-1}$ integrated luminosity, one may reach a $5\sigma$ statistical significance for a heavy quark of mass $580(630)\mathrm{GeV}$ if the heavy quark-Standard Model quark mixing parameter is order one.

Results of a next-to-leading order calculation of the inclusive cross section for a photon and a heavy quark (charm or bottom), $p\overline{p}/pp\to \gamma +Q+X$, are presented. Pointlike photon subprocesses through $\mathcal{O}(\alpha {\alpha }_s^2)$ and fragmentation subprocesses through $\mathcal{O}({\alpha }_s^3)$ are included. The calculation is performed using a phase space slicing technique so that the effects of experimental cuts can be included. Results for the ratios of the charm and bottom cross sections are presented, and the systematics of the various subprocesses for both the Tevatron and the LHC are compared and contrasted.

The Higgs boson production in association with a pair of $W$ bosons at the Large Hadron Collider (LHC) can be used to probe the coupling between the Higgs boson and vector gauge bosons and discover the signature of new physics. We describe the impact of the complete QCD next-to-leading order (NLO) radiative corrections and the gluon-gluon fusion subprocesses to the cross section of this process at the LHC and investigate the dependence of the leading order (LO) and QCD corrected cross sections on the factorization/renormalization energy scale and Higgs boson mass. We present the LO and QCD corrected distributions of the invariant mass of a $W$ boson pair and the transverse momenta of the final $W$ and Higgs boson. We find that the QCD NLO corrections and the contribution from a gluon-gluon fusion subprocess significantly modify the LO distributions, and the scale dependence of the QCD corrected cross section is badly underestimated by the LO results. Our numerical results show that the $K$-factor of the QCD correction varies from 1.48 to 1.64 when $m_H$ goes up from 100 GeV to 160 GeV. We find also the QCD correction from the $gg\to H^0{W}^{+}{W}^{-}$ subprocess at the LHC is significant and should be considered in precise experiment.

Estimates of the light hadron masses, decay constants, and couplings in AdS/QCD models are generally more accurate than should have been expected. Certain predictions based on the AdS/CFT correspondence, such as the ratio of the equilibrium viscosity to entropy density, are universal and therefore provide firm experimental tests of these models. Other observables, while not completely universal, may be relatively insensitive to model details. We calculate the dependence of a number of low-energy hadronic observables on details of the hard-wall AdS/QCD model. In particular, we vary the infrared boundary conditions, the 5D gauge coupling, and the mass of the field responsible for chiral symmetry breaking, while holding fixed a small number of observables. We also find a generalized Gell-Mann–Oakes–Renner relation which helps to justify the identification of model parameters with the product of the physical quark mass and chiral condensate as per the AdS/CFT correspondence.

We consider early time cosmic evolution in string gas cosmology dominated by open strings attached to D-branes. After reviewing statistical properties of open strings in D-brane backgrounds, we use dilaton-gravity equations to determine the string frame fields. Although, there are distinctions in the Hagedorn regime thermodynamics and dilaton coupling as compared to closed strings, it seems difficult to avoid Jeans instability and assume thermal equilibrium simultaneously, which is already a known problem for closed strings. We also examine characteristics of a possible subsequent large radius regime in this setup.

Based on the choice of a special gauge, in which a useful form of scaling invariance holds, a new method is suggested for the analytic, nonperturbative calculation of the $n$-point functions of QED. A modified functional analysis is employed in configuration space, where the dressed electron and photon propagators (in quenched approximation) are each found to be simple products of the relevant free propagator with an appropriate function of configuration space variables containing all powers of the square of the coupling constant.

The renormalizability of the three dimensional supersymmetric $C{P}^{N-1}$ model is discussed in the $1/N$-expansion method, to all orders of $1/N$. The model has $N$ copies of the dynamical field and the amplitudes are expanded in powers of $1/N$. In order to see the effects of supersymmetry explicitly, Feynman rules for superfields are used. All divergences in amplitudes can be eliminated by the renormalizations of the coupling constant and the wave function of the dynamical field to all orders of $1/N$. The beta function of the coupling constant is also calculated to all orders of $1/N$. It is shown that this model has a nontrivial ultraviolet fixed point. The beta function is shown to have no higher order correction in the $1/N$-expansion.

Signatures of lensing of the cosmic microwave background radiation by gravitational potentials along the line of sight carry with them information on the matter distribution, neutrino masses, and dark energy properties. We examine the constraints that Planck, PolarBear, and CMBpol future data, including from the B-mode polarization or the lensing potential, will be able to place on these quantities. We simultaneously fit for neutrino mass and dark energy equation of state including time variation and early dark energy density, and compare the use of polarization power spectra with an optimal quadratic estimator of the lensing. Results are given as a function of systematics level from residual foreground contamination. A realistic CMBpol experiment can effectively constrain the sum of neutrino masses to within 0.05 eV and the fraction of early dark energy to 0.002. We also present a surprisingly simple prescription for calculating dark energy equation of state constraints in combination with supernova distances from JDEM.

In loop quantum cosmology, Friedmann-LeMaître-Robertson-Walker space-times arise as well-defined approximations to specific quantum geometries. We initiate the development of a quantum theory of test scalar fields on these quantum geometries. Emphasis is on the new conceptual ingredients required in the transition from classical space-time backgrounds to quantum space-times. These include a “relational time” à la Leibniz, the emergence of the Hamiltonian operator of the test field from the quantum constraint equation, and ramifications of the quantum fluctuations of the background geometry on the resulting dynamics. The familiar quantum field theory on classical Friedmann-LeMaître-Robertson-Walker models arises as a well-defined reduction of this more fundamental theory.

In previous work, $q$-theory was introduced to describe the gravitating macroscopic behavior of a conserved microscopic variable $q$. In this article, the gluon condensate of quantum chromodynamics is considered in terms of $q$-theory. The remnant vacuum energy density (i.e., cosmological constant) of an expanding universe is estimated as $K_{\mathrm{QCD}}^3/E_{\mathrm{Planck}}^2$, with string tension $K_{\mathrm{QCD}}\approx ({10}^2\mathrm{MeV}{)}^2$ and gravitational scale $E_{\mathrm{Planck}}\approx {10}^{19}\mathrm{GeV}$. The only input for this estimate is general relativity, quantum chromodynamics, and the Hubble expansion of the present Universe.