Dark matter annihilation in Galactic substructure will imprint characteristic angular signatures on the all-sky map of the diffuse gamma-ray background. We study the gamma-ray background anisotropy due to the subhalos and discuss detectability at the Fermi Gamma-ray Space Telescope. In contrast to earlier work that relies on simulated all-sky maps, we derive analytic formulae that enable to directly compute the angular power spectrum, given parameters of subhalos such as mass function, and radial profile of gamma-ray luminosity. As our fiducial subhalo models, we adopt $M^{-1.9}$ mass spectrum, subhalos radial distribution suppressed toward the Galactic center, and luminosity profile of each subhalo dominated by its smooth component. We find that, for multipole regime corresponding to $\theta \lesssim 5°$, the angular power spectrum is dominated by a noiselike term, with suppression due to internal structure of relevant subhalos. If the mass spectrum extends down to Earth-mass scale, then the subhalos would be detected in the anisotropy with Fermi at angular scales of $\sim 10°$, if their contribution to the gamma-ray background is larger than $\sim 20\%$. If the minimum mass is around ${10}^4{M}_{\odot }$, on the other hand, the relevant angular scale for detection is $\sim 1°$, and the anisotropy detection requires that the subhalo contribution to the gamma-ray background intensity is only $\sim 4\%$. These can be achieved with a modest boost for particle-physics parameters. We also find that the anisotropy analysis could be a more sensitive probe for the subhalos than individual detection. We also study dependence on model parameters, where we reach the similar conclusions for all the models investigated. The analytic approach should be very useful when Fermi data are analyzed, and the obtained angular power spectrum is interpreted in terms of subhalo models.

We study the problem of extracting information about composition and equation of state of dense matter in neutron star interior using axial $w$ modes. We determine complex frequencies of axial $w$ modes for a set of equations of state involving hyperons as well as Bose-Einstein condensates of antikaons adopting the continued fraction method. Hyperons and antikaon condensates result in softer equations of state leading to higher frequencies and lower damping times of first axial $w$ modes than those of the nuclear matter case. The presence of condensates may lead to the appearance of a new stable branch of superdense stars beyond the neutron star branch called the third family. The existence of the same mass compact stars in both branches is known as neutron star twins. Further investigation of twins reveals that first axial $w$-mode frequencies of superdense stars in the third family are higher than those of the corresponding twins in the neutron star branch.

Extensive air showers are generated through interactions of high-energy cosmic rays impinging the Earth’s atmosphere. A new method is described to infer the attenuation of hadrons in air showers. The numbers of electrons and muons, registered with the scintillator array of the KASCADE experiment, are used to estimate the energy of the shower inducing primary particle. A large hadron calorimeter is used to measure the hadronic energy reaching observation level. The ratio of energy reaching ground level to the energy of the primary particle is used to derive an attenuation length of hadrons in air showers. In the energy range from ${10}^6$ to $3\times {10}^7\mathrm{GeV}$ the attenuation length obtained increases from 170 to $210\mathrm{g}/{\mathrm{cm}}^2$. The experimental results are compared to predictions of simulations based on contemporary high-energy interaction models.

We study the sensitivity for testing the anomalous triple gauge couplings $ZZ\gamma$ and $Z\gamma \gamma$ via the process $e^{+}{e}^{-}\to \nu \overline{\nu }\gamma$ at high energy linear colliders. For integrated luminosities of $500{\mathrm{fb}}^{-1}$ and center of mass energies between 0.5 and 1.5 TeV, we find that this process can provide tests of the triple neutral gauge boson couplings of order ${10}^{-4}$, 1 order of magnitude lower than the standard model prediction.

The supernumerous $\eta (1405)$ is considered a strong candidate for the pseudoscalar glueball. In a phenomenological chiral approach, we consider a mixing scenario of bare pseudoscalar $n\overline{n}$ and $s\overline{s}$ quarkonia with the glueball. We study the decay properties and point out the peculiarities of this scenario in order to support the possible identification of the $J^{\mathrm{PC}}=0^{-+}$ glueball.

The relativistic corrections of order $v^2$ to the fragmentation functions for the heavy quark to $S$-wave heavy quarkonia are calculated in the framework of the nonrelativistic quantum chromodynamics factorization formula. We derive the fragmentation functions by using the Collins-Soper definition in both the Feynman gauge and the axial gauge. We also extract them through the process $Z^0\to Hq\overline{q}$ in the limit $M_Z/m\to \infty$. We find that all results obtained by these two different methods and in different gauges are the same. We estimate the relative size of the relativistic corrections to the fragmentation functions.

Within the minimal supersymmetric model (MSSM) and standard model (SM) frameworks, we analyze the 1loop electroweak predictions for the helicity amplitudes describing the 17 processes $gg\to H{H}^{\prime }$, and the 9 processes $gg\to VH$; where $H$, $H^{\prime }$ denote Higgs or Goldstone bosons, while $V=Z$, $W^{\pm }$. Concentrating on MSSM, we then investigate how the asymptotic helicity conservation (HCns) property of supersymmetry (SUSY) affects the amplitudes at the LHC energy range and what is the corresponding situation in the SM, where no HCns theorem exists. HCns is subsequently used to construct many relations among the cross sections of the above MSSM processes, depending only on the standard MSSM angles $\alpha$ and $\beta$ characterizing the two Higgs doublets. These relations should be asymptotically exact but as the energy decreases toward the LHC range, mass-depending deviations should start appearing. Provided the SUSY scale is not too high, these relations may remain roughly correct, even at the LHC energy range.

We describe searches for $B^0$ meson decays to the charmless final states ${\pi }^0{K}_S^0{K}_S^0$, $\eta K_S^0{K}_S^0$, and ${\eta }^{\prime }{K}_S^0{K}_S^0$. The data sample corresponds to $467\times {10}^6$ $B\overline{B}$ pairs produced in $e^{+}{e}^{-}$ annihilation and collected with the BABAR detector at the SLAC National Accelerator Laboratory. We find no significant signals and determine the 90% confidence level upper limits on the branching fractions, in units of ${10}^{-7}$, $\mathcal{B}(B^0\to {\pi }^0{K}_S^0{K}_S^0)<9$, $\mathcal{B}(B^0\to \eta K_S^0{K}_S^0)<10$, and $\mathcal{B}(B^0\to {\eta }^{\prime }{K}_S^0{K}_S^0)<20$.

The heat capacities and the electric capacitances of charged Bañados-Teitelboim-Zanelli (BTZ) black hole are first calculated. By using the equilibrium fluctuation theory of thermodynamics the second-order moments in three different ensembles are obtained, and it is found that in the microcanonical ensemble the extremal charged BTZ black hole is a critical point of the second-order phase transition. The critical exponents associated with some response coefficients satisfy the scaling law of the first kind and the effective spatial dimension is determined to be one from the scaling law of the second kind. The Ricci curvature scalar associated with the Ruppeiner thermodynamic metric is calculated, which suggests also that the effective spatial dimension of the charged BTZ black hole is one.

We find and analyze solutions of Einstein’s equations in arbitrary dimensions and in the presence of a scalar field with a Liouville potential coupled to a Maxwell field. We consider spacetimes of cylindrical symmetry or again subspaces of dimension $d-2$ with constant curvature and analyze in detail the field equations and manifest their symmetries. The field equations of the full system are shown to reduce to a single or couple of ordinary differential equations, which can be used to solve analytically or numerically the theory for the symmetry at hand. Further solutions can also be generated by a solution-generating technique akin to the electromagnetic duality in the absence of a cosmological constant. We then find and analyze explicit solutions including black holes and gravitating solitons for the case of four-dimensional relativity and the higher-dimensional oxidized five-dimensional spacetime. The general solution is obtained for a certain relation between couplings in the case of cylindrical symmetry.

We find a unique way of realizing inflation through cyclic phases in a universe with negative vacuum energy. According to the second law of thermodynamics entropy monotonically increases from cycle to cycle, typically by a constant factor. This means that the scale factor at the same energy density in consecutive cycles also increases by a constant factor. If the time period of the oscillations remains approximately constant then this leads to an “overall” exponential growth of the scale factor, mimicking inflation. A graceful exit from this inflationary phase is possible as a dynamical scalar field can take us from the negative to a positive energy vacuum during the last contracting phase.

We study the flux and the angular power spectrum of gamma rays produced by dark matter (DM) annihilations in the Milky Way (MW) and in extra-galactic halos. The annihilation signal receives contributions from: (a) the smooth MW halo, (b) resolved and unresolved substructures in the MW, (c) external DM halos at all redshifts, including (d) their substructures. Adopting a self-consistent description of local and extra-galactic substructures, we compute the angular power spectrum of gamma-ray anisotropies and show that, quite independently from the prescription used for the concentration parameters $c(M,z)$, an interesting signature of DM annihilations could soon be discovered by the Fermi LAT satellite at low multipoles, $\ell \sim 100$, assuming a particle physics scenario that does not violate gamma-ray constraints from the Galactic center. The DM contribution to the angular power spectrum is dominated by MW substructures (with mass $M\ge {10}^4{M}_{\odot }$), while, at least for the substructures’ models that we have adopted, the contribution of extra-galactic annihilations is negligible at all scales. MW subhalos also dominate the annihilation flux in the majority of the sky, with the smooth galactic halo being brighter only in the very central region.

We study the annihilating dark matter contribution to the extragalactic diffuse gamma-ray background spectrum, motivated by the recent observations of cosmic-ray positron/electron anomalies. The observed diffuse gamma-ray flux provides stringent constraint on dark matter models and we present upper bounds on the annihilation cross section of the dark matter. It is found that for the case of cored dark matter halo profile, the diffuse gamma-rays give more stringent bound compared with gamma-rays from the Galactic center. The Fermi satellite will make the bound stronger.

We construct an axion model for generating isocurvature fluctuations with blue spectrum, $n_{\mathrm{iso}}=2–4$, which is suggested by recent analyses of admixture of adiabatic and isocurvature perturbations with independent spectral indices, $n_{\mathrm{ad}}\ne n_{\mathrm{iso}}$. The distinctive feature of the model is that the spectrum is blue at large scales while scale invariant at small scales. This is naturally realized by the dynamics of the Peccei-Quinn scalar field.

We consider the prospects for dark matter/energy unification in k-essence type cosmologies. General mappings are established between the k-essence scalar field, the hydrodynamic and braneworld descriptions. We develop an extension of the general relativistic dust model that incorporates the effects of both pressure and the associated acoustic horizon. Applying this to a tachyon model, we show that this inhomogeneous “variable Chaplygin gas” does evolve into a mixed system containing cold dark matter like gravitational condensate in significant quantities. Our methods can be applied to any dark energy model, as well as to mixtures of dark energy and traditional dark matter.

We present the results of Monte Carlo simulations of three-dimensional electromagnetic cascade initiated by interactions of the multi-TeV $\gamma$ rays with the cosmological infrared/optical photon background in the intergalactic medium. Secondary electrons in the cascade are deflected by the intergalactic magnetic fields before they scatter on CMB photons. This leads to extended 0.1°–10° scale emission at multi-GeV and TeV energies around extragalactic sources of very high-energy $\gamma$ rays. The morphology of the extended emission depends, in general, on the properties of magnetic fields in the intergalactic medium. Using Monte Carlo simulated data sets, we demonstrate that the decrease of the size of extended source with the increase of energy allows to measure weak magnetic fields with magnitudes in the range from $\le {10}^{-16}\mathrm{G}$ to ${10}^{-12}\mathrm{G}$ if they exist in the voids of the large scale structure.

A primordial magnetic field in the early universe will cause Faraday rotation of the linear polarization of the cosmic microwave background generated via Compton scattering at the surface of last scattering. This rotation induces a nonzero parity-odd (B-mode) polarization component. The Wilkinson Microwave Anisotropy Probe 5-year data puts an upper limit on the magnitude of the B-polarization power spectrum; assuming that the B-polarization signal is totally due to the Faraday rotation effect, the upper limits on the comoving amplitude of a primordial stochastic magnetic field range from $6\times {10}^{-8}$ to $2\times {10}^{-6}\mathrm{G}$ on a comoving length scale of 1 Mpc, depending on the power spectrum of the magnetic field.

We examine the class of barotropic fluid models of dark energy, in which the pressure is an explicit function of the density, $p=f(\rho )$. Through general physical considerations we constrain the asymptotic past and future behaviors and show that this class is equivalent to the sum of a cosmological constant and a decelerating perfect fluid, or “aether,” with $w_{\mathrm{AE}}\ge 0$. Barotropic models give substantially disjoint predictions from quintessence, except in the limit of $\Lambda \mathrm{CDM}$. They are also interesting in that they simultaneously can ameliorate the coincidence problem and yet “predict” a value of $w\approx -1$.

We use stellar dynamics arguments to constrain the relevant parameters of unparticle-inspired models of gravity. We show that resulting bounds do constrain the parameters of the theory of unparticles, as far as its energy scale satisfies the condition ${\Lambda }_U\ge 1\mathrm{TeV}$ and $d_U$ is close to unity.

We study a model for leptogenesis in which the total $CP$ asymmetries in the decays and scatterings involving the $SU(2)$ singlet seesaw neutrinos $N_{\alpha }$ vanish (${ϵ}_{N_{\alpha }}=0$). Leptogenesis is possible due to nonvanishing $CP$ violating lepton flavor asymmetries, realizing a situation in which the baryon asymmetry is due exclusively to flavor effects. We study the production of a net lepton asymmetry by solving the Boltzmann equations specific to this model, and we show that successful leptogenesis can be obtained at a scale as low as the TeV. We also discuss constraints on the model parameter space arising from current experimental upper limits on lepton flavor violating decays.