With the solar and SN87 neutrino observations as proofs of concepts, the kilometer-scale neutrino experiment IceCube will scrutinize its data for new particle physics. In this paper we review the prospects for the realization of such a program. We begin with a short overview of the detector response and discuss the reach of ``beam'' luminosity. After that we discuss the potential of IceCube to probe deviations of neutrino-nucleon cross sections from the Standard Model predictions at center-of-mass energies well beyond those accessible in man-made accelerators. Then we review the prospects for extremely long-baseline analyses and discuss the sensitivity to measure tiny deviations of the flavor mixing angle, expected to be induced by quantum gravity effects. Finally we discuss the potential to uncover annihilation of dark matter particles gravitationally trapped at the center of the Sun, as well as processes occurring in the early Universe at energies close to the Grand Unification scale.

The electron-neutrino bremsstrahlung process has been considered in the framework of electro-weak theory. The scattering cross section has been calculated in the center of mass frame and approximated to extreme relativistic as well as non-relativistic case. The rate of energy-loss via this type of bremsstrahlung process has been obtained both in non-degenerate and degenerate region. The effect of this electron-neutrino bremsstrahlung process in different ranges of temperature and density characterizing the late stages of stellar evolution has been discussed. It is found from our study that this bremsstrahlung process is highly important in the extreme relativistic non-degenerate region. It has also been observed that in the extreme degenerate region the process might be more effective compared to the non-degenerate case.

It is shown by an explicit calculation that the excitations about the self-accelerating cosmological solution of the Dvali--Gabadaze--Porrati model contain a ghost mode. This raises serious doubts about viability of this solution. Our analysis reveals the similarity between the quadratic theory for the perturbations around the self-accelerating Universe and an Abelian gauge model with two Stueckelberg fields.

I introduce the Fermi Paradox and some of its solutions. Then I present my own solution which includes two proposals called the Subanthropic Principle and the Undetectability Conjecture. After discussing some consequences of this solution, I make some comments about brane world scenarios and their potential to strengthen the Fermi Paradox. Finally, in the appendix I have included some questions and answers that came up during this Forum.

We address the initial conditions for an expanding cosmology using the holographic principle. For the case of a closed model, the old prescription of Fishler and Susskind, that uses the particle horizon to encode the bulk degrees of freedom, can be implemented for accelerated models with enough acceleration. As a bonus we have singularity free bouncing models. The bound is saturated for co-dimension one branes dominated universes.

Affleck-Dine baryogenesis in models where the gravitino is both the lightest supersymmetric particle and the dark matter candidate is investigated. For a high enough reheating temperature to produce sufficient gravitinos by thermal processes, the observed baryon asymmetry can be explained by Affleck-Dine baryogenesis as well as thermal leptogenesis. On the other hand, if the reheating temperature is not high enough, most of the gravitinos must be produced by the decay of the next-to-lightest supersymmetric particle (NSP). Particularly, in the case where Q-balls cannot survive the evaporation, the gravitino number density is given by the NSP's thermal relic density. Interestingly, if Q-balls survive, they can be a source of gravitinos via the NSP decay. Then, we could find a new cosmological interesting region in parameter space because the gravitino number density does not relate to the NSP's thermal relic density.

We have re-analyzed the world data on inclusive polarized DIS, in both NLO and LO QCD, including the new HERMES and COMPASS data. The updated NLO polarized densities are given in both the $\rm \bar{MS}$ and JET schemes. The impact of the new data on the results is discussed.

Modified Newtonian dynamics, an alternative to the cosmic dark matter model, proposed that gravitational field deviates from the Newtonian law when the field strength $g$ is weaker than a critical value $g_0$. We will show that the dynamics of MOND can be derived from an induced gravity model. New dynamics is shown to be compatible with the spatial inhomogeneity of scalar fields coupled to the system. Approximate solutions are shown explicitly for a simple model with a spherically symmetric mass-distribution.

We use the dynamical systems approach to investigate the Bianchi type VIII models with a tilted $\gamma$-law perfect fluid. We introduce expansion-normalised variables and investigate the late-time asymptotic behaviour of the models and determine the late-time asymptotic states. For the Bianchi type VIII models the state space is unbounded and consequently, for all non-inflationary perfect fluids, one of the curvature variables grows without bound. Moreover, we show that for fluids stiffer than dust ($1<\gamma<2$), the fluid will in general tend towards a state of extreme tilt. For dust ($\gamma=1$), or for fluids less stiff than dust ($0<\gamma< 1$), we show that the fluid will in the future be asymptotically non-tilted. Furthermore, we show that for all $\gamma\geq 1$ the universe evolves towards a vacuum state but does so rather slowly, $\rho/H^2\propto 1/\ln t$.

We study the possibility of having a static, asymptotically AdS black hole localized on a braneworld with matter fields, within the framework of the Randall and Sundrum scenario. We attempt to look for such a brane black hole configuration by slicing a given bulk spacetime and taking Z_2 symmetry about the slices. We find that such configurations are possible, and as an explicit example, we provide a family of asymptotically AdS brane black hole solutions for which both the bulk and brane metrics are regular on and outside the black hole horizon and brane matter fields are realistic in the sense that the dominant energy condition is satisfied. We also find that our braneworld models exhibit signature change inside the black hole horizon.

We show that there exist massive perturbative states of the ten dimensional Green-Schwarz closed superstring that are stabilized against collapse due to presence of fermionic zero modes on its worldsheet. The excited fermionic degrees of freedom backreact on the spacetime motion of the string in the same way as a neutral persistent current would, rendering these string loops stable. We point out that the existence of these states could have important consequences as stable loops of cosmological size as well as long lived states within perturbative string theory.

Dark energy dynamics of the universe can be achieved by equivalent mathematical descriptions taking into account generalized fluid equations of state in General Relativity, scalar-tensor theories or modified F(R) gravity in Einstein or Jordan frames. The corresponding technique transforming equation of state description to scalar-tensor or modified gravity is explicitly presented. We show that such equivalent pictures can be discriminated by matching solutions with data capable of selecting the true physical frame.

We study the Non-Linear Born-Infeld(NLBI) scalar field model and quintessence model with two different potentials($V(\phi)=-s\phi$ and ${1/2}m^2\phi^2$). We investigate the differences between those two models. We explore the equation of state parameter w and the evolution of scale factor $a(t)$ in both NLBI scalar field and quintessence model. The present age of universe and the transition redshift are also obtained. We use the Gold dataset of 157 SN-Ia to constrain the parameters of the two models. All the results show that NLBI model is slightly superior to quintessence model.

According to modern developments in turbulence theory, the "dissipation" scales (u.v. cut-offs) $\eta$ form a random field related to velocity increments $\delta_{\eta}u$. In this work we, using Mellin's transform combined with the Gaussain large -scale boundary condition, calculate probability densities (PDFs) of velocity increments $P(\delta_{r}u,r)$ and the PDF of the dissipation scales $Q(\eta, Re)$, where $Re$ is the large-scale Reynolds number. The resulting expressions strongly deviate from the Log-normal PDF $P_{L}(\delta_{r}u,r)$ often quoted in the literature. It is shown that the probability density of the small-scale velocity fluctuations includes information about the large (integral) scale dynamics which is responsible for deviation of $P(\delta_{r}u,r)$ from $P_{L}(\delta_{r}u,r)$. A framework for evaluation of the PDFs of various turbulence characteristics involving spatial derivatives is developed. The exact relation, free of spurious Logarithms recently discussed in Frisch et al (J. Fluid Mech. {\bf 542}, 97 (2005)), for the multifractal probability density of velocity increments, not based on the steepest descent evaluation of the integrals is obtained and the calculated function $D(h)$ is close to experimental data. A novel derivation (Polyakov, 2005), of a well-known result of the multi-fractal theory [Frisch, "Turbulence. {\it Legacy of A.N.Kolmogorov}", Cambridge University Press, 1995)), based on the concepts described in this paper, is also presented.

Spherical accretion flows are simple enough for analytical study, by solution of the corresponding fluid dynamic equations. The solutions of stationary spherical flow are due to Bondi. The questions of the choice of a physical solution and of stability have been widely discussed. The answer to these questions is very dependent on the problem of boundary conditions, which vary according to whether the accretor is a compact object or a black hole. We introduce a particular, simple form of stationary spherical flow, namely, self-similar Bondi flow, as a case with physical interest in which analytic solutions for perturbations can be found. With suitable no matter-flux-perturbation boundary conditions, we will show that acoustic modes are stable in time and have no spatial instability at r=0. Furthermore, their evolution eventually becomes ergodic-like and shows no trace of instability or of acquiring any remarkable pattern.

We apply the Smaller ALignment Index (SALI) method to a 4--dimensional mapping of accelerator dynamics in order to distinguish rapidly, reliably and accurately between ordered and chaotic motion. The main advantage of this index is that it tends {\it exponentially} to zero in the case of chaotic orbits, while it fluctuates around non--zero values in the case of quasiperiodic trajectories. Thus, it avoids the notorious ambiguities concerning the eventual convergence of (maximum) Lyapunov exponents to (positive) non-zero values. Exploiting the different behavior of SALI in these two cases we produce phase space `charts' where regions of chaos and order are clearly identified. Evaluating the percentage of chaotic and escaping orbits as a function of the distance from the origin we are able to estimate rapidly and accurately the boundaries of the {\it dynamical aperture} of a proton beam, passing repeatedly through an array of magnetic focusing elements.

The emission spectrum from a simple accretion disc model around a compact object is compared for the cases of a black hole (BH) and a boson star (BS) playing the role of the central object. It was found in the past that such spectrum presents a hardening at high frequencies, however, here it is shown that the self-interaction and compactness of the BS have the effect of softening the spectrum, the less compact the star is the softer the emission spectrum at high frequencies. Because the mass of the boson fixes the mass of the star and the self-interaction the compactness of the star we find that for certain values of the BSs parameters it is possible to produce similar spectra to those generated when the central object is a BH. This result presents two important implications: i) using this simple accretion model a BS can supplant a BH in the role of compact object accreting matter and ii) within the assumptions of the present accretion disc model we do not find a prediction that could help at distinguishing a BH from a BS with appropriate parameters of mass and self-interaction.

We show that in tilting perfect fluid cosmological models with an ultra-radiative equation of state, generically the tilt becomes extreme at late times and, as the tilt instability sets in, observers moving with the tilting fluid will experience singular behaviour in which infinite expansion is reached within a finite proper time, similar to that of phantom cosmology (but without the need for exotic forms of matter).

A few multiplets that can be added to the SM contain a lightest neutral component which is automatically stable and provides allowed DM candidates with a non-standard phenomenology. Thanks to coannihilations, a successful thermal abundance is obtained for well defined DM masses. The best candidate seems to be a SU(2)_L fermion quintuplet with mass 4.5 TeV, accompanied by a charged partner 166 MeV heavier with life-time 1.8 cm, that manifests at colliders as charged tracks disappearing in pi^\pm with 97.7% branching ratio. The cross section for usual NC direct DM detection is sigma_SI = f^2 1.0 10^-43 cm^2 where f ~ 1 is a nucleon matrix element. We study prospects for CC direct detection and for indirect detection.

It goes without saying that we are stuck with the universe we have. Nevertheless, we would like to go beyond simply describing our observed universe, and try to understand why it is that way rather than some other way. Physicists and cosmologists have been exploring increasingly ambitious ideas that attempt to explain why certain features of our universe aren't as surprising as they might first appear.

The inner layers of a neutron star crust, composed of a Coulomb lattice of neutron rich nuclear clusters immersed in a sea of ``free'' superfluid neutrons, are closely analogous to periodic condensed matter systems such as electronic, photonic or phononic crystals. Applying methods from solid state physics to the neutron star context, we study the transport properties of those ``free'' neutrons for the outermost layers of the inner crust, near the drip point $\rho_{\rm drip} \sim 4\times 10^{11}$ g.cm$^{-3}$. In particular, we evaluate the effective neutron mass resulting from Bragg scattering by a band structure calculation. Comparison is made with the case of electrons in solids. The observational consequences are briefly discussed.