We consider the orbits of particles with spin in the Schwarzschild spacetime. Using the Papapetrou-Dixon equations of motion for spinning particles, we solve for the orbits and focus on those that exhibit chaos using both Poincaré maps and Lyapunov exponents. In particular, we develop a method for comparing the Lyapunov exponents of chaotic orbits. We find chaotic orbits for smaller spin values than previously thought and find chaotic orbits with astrophysically relevant spin values.

We discuss the neutrino constraints from solar and terrestrial dark matter (DM) annihilations in the inelastic dark matter (iDM) scenario after the recent CDMS II results. To reconcile the DAMA/LIBRA data with constraints from all other direct experiments, the iDM needs to be light ($m_{\chi }<100\mathrm{GeV}$) and have a large DM-nucleon cross section (${\sigma }_n\sim {10}^{-4}\mathrm{pb}$ in the spin-independent (SI) scattering and ${\sigma }_n\sim 10\mathrm{pb}$ in the spin-dependent (SD) scattering). The dominant contribution to the iDM capture in the Sun is from scattering off $\mathrm{Fe}/\mathrm{Al}$ in the SI/SD case. Current bounds from Super-Kamiokande exclude the hard DM annihilation channels, such as $W^{+}{W}^{-}$, $ZZ$, $t\overline{t}$, and ${\tau }^{+}{\tau }^{-}$. For soft channels such as $b\overline{b}$ and $c\overline{c}$, the limits are loose, but could be tested or further constrained by future IceCube plus DeepCore. For neutrino constraints from the DM annihilation in the Earth, due to the weaker gravitational effect of the Earth and inelastic capture condition, the constraint exists only for small mass splitting $\delta <40\mathrm{keV}$ and $m_{\chi }\sim (10,50)\mathrm{GeV}$ even in the ${\tau }^{+}{\tau }^{-}$ channel.

We present a new type of brane inflation motivated by multikink solitonic solutions of a scalar field in five dimensions. In the thin brane limit, we analyze a nonstatic configuration in which the distance between two parallel domain walls decreases. We show that the ensuing spacetime is inflationary, both on the branes, and, for certain potentials, in the bulk. We argue that this inflationary regime is transitory and can end via a brane merger into a single kink solution—a flat, thick brane RS2 universe. This scenario is quite general; we show that any potential which supports a single flat kink solution is also likely to support an inflationary multikink configuration.

Several anomalies have been identified that may imply a breakdown of the statistical isotropy of the cosmic microwave background (CMB). In particular, an anomalous alignment of the quadrupole and octopole and a hemispherical power asymmetry have increased in significance as the data have improved. There have been several attempts to explain these observations, which explore isotropy breaking mechanisms within the early universe, but little attention has been given to the possibility that these anomalies have their origin within the local universe. We explore such a mechanism by considering the kinetic Sunyaev-Zel’dovich effect due to a gaseous halo associated with the Milky Way. Considering several physical models of an anisotropic free-electron optical depth contributed by such a halo, we find that the associated screening maps of the primordial anisotropies have the necessary orientations to affect the anomaly statistics very significantly, but only if the column density of free electrons in the halo is at least an order of magnitude higher than indicated by current observations.

In this paper, we explore the properties of gravitational lensing by black holes in the Randall-Sundrum II braneworld. We use numerical techniques to calculate lensing observables using the tidal Reissner-Nordstrom (TRN) and Garriga-Tanaka metrics to examine supermassive black holes and primordial black holes. We introduce a new way to parametrize tidal charge in the TRN metric which results in a large increase in image magnifications for braneworld primordial black holes compared to their 4-dimensional analogs. Finally, we offer a mathematical analysis that allows us to assess the validity of the logarithmic approximation of the bending angle for any static, spherically symmetric metric. We apply this to the TRN metric and show that it is valid for any amount of tidal charge.

We propose an estimator defined in real space for the reconstruction of the weak lensing potential due to the intervening large-scale structure from high resolution maps of the cosmic microwave background. This estimator was motivated as an alternative to the quadratic estimator in harmonic space to surpass the difficulties of the analysis of maps containing galactic cuts and point source excisions. Using maps synthesized by pixel remapping, we implement the estimator for two experiments, namely, one in the absence and one in the presence of detector noise, and compare the reconstruction of the convergence field with that obtained with the quadratic estimator defined in harmonic space. We find good agreement between the input and the reconstructed power spectra using the proposed real space estimator. We discuss interesting features of the real space estimator and future extensions of this work.

Using group theory arguments we extend and complete our previous work by deriving all SU(6) exact wave functions associated with the spectrum of mixed symmetric baryon states $[N_c-1,1]$ in the $1/N_c$ expansion. The extension to SU(6) enables us to study the mass spectra of both strange and nonstrange baryons, while previous work was restricted to nonstrange baryons described by SU(4). The wave functions are specially written in a form to allow a comparison with the approximate, customarily used wave functions, where the system is separated into a ground state core and an excited quark. We show that the matrix elements of the flavor operator calculated with the exact wave functions acquire the same asymptotic form at large $N_c$, irrespective of the spin-flavor multiplet contained in $[N_c-1,1]$, while with the approximate wave function one cannot obtain a similar behavior. The isoscalar factors of the permutation group of $N_c$ particles derived here can be used in any problem where a given fermion system is described by the partition $[N_c-1,1]$, and one fermion has to be separated from the rest.

Considering the coupling of color $1\otimes 1$ and $8\otimes 8$ structures, we calculate the energy of the newly observed $X(3915)$ as an $S$-wave $D^{*}{\overline{D}}^{*}$ state in the Bhaduri, Cohler, and Nogami quark model by the Gaussian expansion method. Because of the color coupling, the bound state of $D^{*}{\overline{D}}^{*}$ with $J^{PC}=0^{++}$ is found, which is well consonant with the experimental data of the $X(3915)$. The bound states of $B^{*}{\overline{B}}^{*}$ with $J^{PC}=0^{++}$ and $2^{++}$ are also predicted in this work.

In this paper, a study of light-cone distribution amplitudes (LCDAs) for $s$-wave heavy meson are presented in both general and heavy quark frameworks. Within the light-front approach, the leading twist light-cone distribution amplitudes, ${\varphi }_M(u)$, and their relevant decay constants of heavy pseudoscalar and vector mesons, $f_M$, have simple relations. These relations can be further simplified when the heavy quark limit is taken into consideration. After fixing the parameters that appear in both Gaussian and power-law wave functions, the corresponding decay constants are calculated and compared with those of other theoretical approaches. The curves and the first six $\xi$-moments of ${\varphi }_M(u)$ are plotted and estimated. A conclusion is drawn from these results: Even though the values of the decay constants of the distinct mesons are almost equal, the curves of their LCDAs may have quite large differences, and vice versa. Additionally, in the heavy quark limit, the leading twist LCDAs, ${\Phi }_{Qq}(\omega )$ and ${\Phi }_{Qq}(\omega )$, are compared with the $B$-meson LCDAs, ${\psi }_{+}(\omega )$, suggested by the other theoretical groups.

In seesaw models with more than one generation of light and heavy neutrinos, $\nu$ and $N$, respectively, it is possible to have sizable mixing between them for heavy-neutrino masses of order 100 GeV or less. We explore this possibility further, taking into account current experimental constraints, and study its effect on Higgs-boson decays in the contexts of seesaw models of types I and III. We find that in the type-I case the Higgs decay into a pair of light and heavy neutrinos, $h\to \nu N$, could increase the total Higgs width in the standard model by up to almost 30% for a relatively light Higgs-boson, which would significantly affect Higgs searches at the LHC. The subsequent prompt decay of $N$ into three light fermions makes this Higgs decay effectively a four-body decay. We further find that, in the presence of the large light-heavy mixing, these four-body Higgs decays can have rates a few times larger than their standard-model counterparts and therefore could provide a potentially important window to reveal the underlying seesaw mechanism.

We present a new measurement of the unitarity triangle angle ${\varphi }_3$ using a Dalitz plot analysis of the $K_S^0{\pi }^{+}{\pi }^{-}$ decay of the neutral $D$ meson produced in $B^{\pm }\to D^{(*)}{K}^{\pm }$ decays. The method exploits the interference between $D^0$ and ${\overline{D}}^0$ to extract the angle ${\varphi }_3$, strong phase $\delta$, and the ratio $r$ of suppressed and allowed amplitudes. We apply this method to a $605{\mathrm{fb}}^{-1}$ data sample collected by the Belle experiment. The analysis uses three decays: $B^{\pm }\to D{K}^{\pm }$, and $B^{\pm }\to D^{*}{K}^{\pm }$ with $D^{*}\to D{\pi }^0$ and $D^{*}\to D\gamma$, as well as the corresponding charge-conjugate modes. From a combined maximum likelihood fit to the three modes, we obtain ${\varphi }_3={78.4}^{°}\genfrac{}{}{0ex}{}{+10.8°}{-11.6°}\pm 3.6°(\mathrm{syst})\pm 8.9°(\mathrm{\text{model}})$. $CP$ conservation in this process is ruled out at the confidence level $(1-CL)=5\times {10}^{-4}$, or 3.5 standard deviations.

The SciBooNE Collaboration reports a measurement of neutral current coherent ${\pi }^0$ production on carbon by a muon neutrino beam with average energy 0.8 GeV. The separation of coherent from inclusive ${\pi }^0$ production has been improved by detecting recoil protons from resonant ${\pi }^0$ production. We measure the ratio of the neutral current coherent ${\pi }^0$ production to total charged current cross sections to be $(1.16\pm 0.24)\times {10}^{-2}$. The ratio of charged current coherent ${\pi }^{+}$ to neutral current coherent ${\pi }^0$ production is calculated to be ${0.14}_{-0.28}^{+0.30}$, using our published charged current coherent pion measurement.

Spacetime curvature plays the primary role in general relativity but Einstein later considered a theory where torsion was the central quantity. Just as the Einstein-Hilbert action in the Ricci curvature scalar $R$ can be generalized to $f(R)$ gravity, we consider extensions of teleparallel, or torsion scalar $T$, gravity to $f(T)$ theories. The field equations are naturally second order, avoiding pathologies, and can give rise to cosmic acceleration with unique features.

Inspired by the condensed-matter analogues of black holes, we study the quantum correlations across the event horizon reflecting the entanglement between the outgoing particles of the Hawking radiation and their in-falling partners. For a perfectly covariant theory, the total correlation is conserved in time and piles up arbitrary close to the horizon in the past, where it merges into the singularity of the vacuum two-point function at the light cone. After modifying the dispersion relation (i.e., breaking Lorentz invariance) for large $k$, on the other hand, the light cone is smeared out and the entanglement is not conserved but actually created in a given rate per unit time.

We study the evolution of linear density fluctuations of free-streaming massive neutrinos at redshift of $z<1000$, with an explicit justification on the use of a fluid approximation. We solve the collisionless Boltzmann equation in an Einstein de-Sitter (EdS) universe, truncating the Boltzmann hierarchy at $l_{\max }=1$ and 2, and compare the resulting density contrast of neutrinos ${\delta }_{\nu }^{\mathrm{fluid}}$ with that of the exact solutions of the Boltzmann equation that we derive in this paper. Roughly speaking, the fluid approximation is accurate if neutrinos were already nonrelativistic when the neutrino density fluctuation of a given wave number entered the horizon. We find that the fluid approximation is accurate at subpercent levels for massive neutrinos with $m_{\nu }>0.05\mathrm{eV}$ at the scale of $k\lesssim 1.0h{\mathrm{Mpc}}^{-1}$ and redshift of $z<100$. This result validates the use of the fluid approximation, at least for the most massive species of neutrinos suggested by the neutrino oscillation experiments. We also find that the density contrast calculated from fluid equations (i.e., continuity and Euler equations) becomes a better approximation at a lower redshift, and the accuracy can be further improved by including an anisotropic stress term in the Euler equation. The anisotropic stress term effectively increases the pressure term by a factor of $9/5$.

“Eternal inflation” is a term that describes a number of different phenomena that have been classified by Winitzki. According to Winitzki’s classification, these phases can be characterized by the topology of the percolating structures in the inflating, “white,” region. In this paper we discuss these phases, the transitions between them, and the way they are seen by a “Census Taker,” a hypothetical observer inside the noninflating, “black,” region. We discuss three phases that we call “black island,” “tubular,” and “white island.” The black island phase is familiar, composed of rare Coleman De Luccia bubble nucleation events. The Census Taker sees an essentially spherical boundary, described by the conformal field theory of the Friedmann-Robertson-Walker/conformal field theory (FRW/CFT) correspondence. In the tubular phase the Census Taker sees a complicated infinite genus structure composed of arbitrarily long tubes. The white island phase is even more mysterious from the black side. Surprisingly, when viewed from the noninflating region this phase resembles a closed, positively curved universe that eventually collapses to a singularity. Nevertheless, pockets of eternal inflation continue forever. In addition, there is an “aborted” phase in which no eternal inflation takes place. Rigorous results of Chayes, Chayes, Grannan, and Swindle establish the existence of all of these phases, separated by first order transitions, in Mandelbrot percolation, a simple model of eternal inflation.

Chiral perturbation theory predicts that in quantum chromodynamics (QCD), light dynamical quarks suppress the gauge-field topological susceptibility of the vacuum. The degree of suppression depends on quark multiplicity and masses. It provides a strong consistency test for fermion formulations in lattice QCD. Such tests are especially important for staggered fermion formulations that lack a full chiral symmetry and use the “fourth-root” procedure to achieve the desired number of sea quarks. Over the past few years we have measured the topological susceptibility on a large database of 18 gauge-field ensembles, generated in the presence of $2+1$ flavors of dynamical asqtad quarks with up and down quark masses ranging from 0.05 to 1 in units of the strange quark mass and lattice spacings ranging from 0.045 fm to 0.12 fm. Our study also includes three quenched ensembles with lattice spacings ranging from 0.06 to 0.12 fm. We construct the topological susceptibility from the integrated point-to-point correlator of the discretized topological charge density $F\tilde{F}$. To reduce its variance, we model the asymptotic tail of the correlator. The continuum extrapolation of our results for the topological susceptibility agrees nicely at small quark mass with the predictions of lowest-order SU(3) chiral perturbation theory, thus lending support to the validity of the fourth-root procedure.

In this paper, the lepton flavor violating $\tau \to \ell P(V)$ ($P$, $V={\pi }^0$, $\eta$, ${\eta }^{\prime }$, ${\rho }^0$, $\omega$, $\varphi$) and $\tau \to 3\ell$ ($\ell =e$, $\mu$) decays are studied in the framework of the type-III seesaw model, in which new triplet fermions with a zero hypercharge ($Y=0$) interact with ordinary lepton doublets via Yukawa couplings, and affect tree-level leptonic $Z$-boson couplings. We investigate the experimental bound from the leptonic $Z$ decay to get constraints on the existing parameters space. We predict that the upper limits on the branching ratios of $\tau \to \ell P(V)$ and $\tau \to 3\ell$ can reach the experimental current limits.

We examine the $B\to D^{*}$ form factor at zero recoil using a continuum QCD approach rooted in the heavy quark sum rules framework. A refined evaluation of the radiative corrections as well as the most recent estimates of higher-order power terms together with more careful continuum calculation are included. An upper bound on the form factor of $\mathcal{F}(1)\lesssim 0.93$ is derived, based on just the positivity of inelastic contributions. A model-independent estimate of the inelastic contributions shows they are quite significant, lowering the form factor by about 6% or more. This results in an unbiased estimate $\mathcal{F}(1)\approx 0.86$ with about 3% uncertainty in the central value.