The current experimental values for neutrino mixing angles are very close to the predictions of the so-called ``tri-bimaximal'' mixing matrix. I will describe a recent model which gives rise to, for the first time, the tri-bimaximal neutrino mixing and realistic quark CKM matrix simultaneously. The model is based on SU(5) GUT combined with the double tetrahedral group as a family symmetry, and it has only nine parameters to account for all 18 fermion masses and mixing angles. The model also predicts a new sum rule relating the solar mixing angle for the neutrinos and the Cabibbo angle in the quark sector, as a result of the Georgi-Jarlskog relations. The double tetrahedral group may be originated from extra dimensions as a residual symmetry upon orbifold compactification.

We consider the phase transition of a string with tension to a string with a smaller tension . The transition proceeds through quantum tunneling, and we calculate in arbitrary number of dimensions the pre-exponential factor multiplying the leading semiclassical exponential expression for the rate of the process. At the found formula for the decay rate also describes a break up of a metastable string into two pieces.

We study deformations of the Randall--Sundrum 2 model with broken bulk Lorentz invariance. First, we prove a theorem which forbids a static smooth five-dimensional background to exist provided that null energy conditions for a matter on a brane and in a bulk are satisfied. However, if the Lorentz invariance is unbroken such a setup exists. Second, we derive perturbation spectra of scalar and spin-1/2 fermion particles in the backgrounds in question and show that, in spite of the full theory is manifestly not Lorentz invariant, the effective four-dimensional theory can be made approximately Lorentz invariant at low energies. We also investigate localization of particles on a brane in various scenarios with broken Lorentz invariance.

Local oscillations of the brane world are manifested as massive vector fields. Their coupling to the Standard Model can be obtained using the method of nonlinear realizations of the spontaneously broken higher dimensional space-time symmetries, and to an extent, are model independent. Phenomenological limits on these vector field parameters are obtained using current collider data and dark matter constraints. The reach of a future linear collider and the LHC to further investigate the parameter space is determined.

The modification of Einstein gravity at high energies is mandatory from a quantum approach. In this talk, I will point out that this modification necessarily introduces new degrees of freedom. We will discuss the possibility that these new gravitational states can provide the main contribution to the non-baryonic dark matter of the Universe. I will illustrate this idea with the simplest high energy modification of the Einstein-Hilbert action: R2-gravity.

We propose a simple extension of the Minimal Supersymmetric Standard Model which gives rise to thermal inflation, baryogenesis and dark matter in a natural and remarkably consistent way. We consider the λ_φ = 0 special case of our previous model, which is the minimal way to incorporate a Peccei-Quinn symmetry. The axino becomes the lightest supersymmetric particle with $m_{\tilde{a}} \sim 1 \textrm{ to } 10 \GeV$ and is typically over-produced during the flaton decay.
Interestingly though, the dark matter abundance is minimized for , $f_a \sim 10^{11} \textrm{ to } 10^{12} \GeVand |\mu| \sim 400 \GeV \textrm{ to } 1 \TeV$ at an abundance coincident with the observed abundance and with significant amounts of both axions and axinos. Futhermore, for these values the baryon abundance naturally matches the observed abundance.
As an observable, thermal inflation which is the key idea of the model produces a background of gravitational waves.
It is likely to be detected at BBO and DECIGO style direct detection experiments.

We study supersymmetric models that include a viable dark
matter candidate and that generate the observed baryon asymmetry of the Universe at the electro-weak phase transition. We focus on the possibility of probing these models with searches for the permanent electric dipole moment (EDM) of the electron, with direct and indirect dark matter searches, with high energy colliders and with Gravitational Wave detection. We point out that the lightest neutralino might play a key role for the generation of both baryonic and dark matter. We show that models
overproducing relic neutralinos put tighter constraints on successful electro-weak baryogenesis. We present new results on two-loop electric dipole moments and investigate in detail the entire parameter space of the minimal supersymmetric extension of the standard model where electro-weak baryogenesis can account for the baryon asymmetry of the universe. We claim that the ensemble of experimental tests we consider makes ours a
testable framework for the origin of both the dark matter and the baryonic matter-antimatter asymmetry in the Universe.

Minimal extensions of the scalar sector of the SM can be obtained in order to explore neutrino physics. In particular we are interested in scenarios where the seesaw mechanism for neutrino mass generation could be tested at colliders, thus requiring the right-handed neutrinos to have electroweak scale masses. We present two simple realizations of this type of scheme and explore their scalar phenomenology.

The first phase of stellar evolution in the history of the universe may be Dark Stars, powered by dark matter heating rather than by fusion. Weakly interacting massive particles, which are their own antiparticles, can annihilate and provide an important heat source for the first stars in the the universe. This talk presents the story of these Dark Stars. We make predictions that the first stars are very massive (\sim 800 M_\odot), cool (6000 K), bright (\sim 10^6 L_\odot), long-lived (10^6 years), and probable precursors to (otherwise unexplained) supermassive black holes. Later, once the initial DM fuel runs out and fusion sets in, DM annihilation can predominate again if the scattering cross section is strong enough, so that Dark Stars may persist for a very long time.