Cosmology

We point out that the strong CP problem can be resolved by the anthropic principle. The key ideas are to allow explicit breaking(s) of the Peccei-Quinn symmetry which connects the problem to the cosmological constant problem, and to conjecture that the probability distribution of the vacuum energy in the landscape is hierarchical. The axion acquires a large mass from the explicit breaking, and does not contribute to the dark matter abundance. The axion may dominate the energy density of the universe after inflation and reheat the universe by the decay, possibly generating the density perturbations. On the other hand, the axion can be integrated out during inflation, if the explicit breaking is strong enough. All the cosmological problems of the (s)axion with a large Peccei-Quinn scale can be solved.

Many modified gravity schemes predict a non-zero difference (``gravitational slip\'\') between the Newtonian and longitudinal perturbed metric potentials. Such a slip would affect the growth of large scale structure without altering the expansion history of the universe. We quantify the slip with a new parameter varpi, show the effect of non-zero varpi on the growth of cosmic overdensities, and constrain its value using CMB and weak lensing data.

I will discuss recent results from the Cosmic Shear component of the CFHT Legacy Survey. These results reach very large scales, allowing a measurement of poper spectrum of matter fluctuations in the linear regime, and of cosmological parameters.

Moduli stabilization, SUSY breaking and flavor structure are discussed in 5D gauged supergravity models with two vector-multiplet moduli fields. One modulus field makes the fermion mass hierarchy while the other is relevant to the SUSY breaking mediation. We analyse the potential for the moduli from the viewpoint of the 4D effective theory to obtain the stabilized values of the moduli and their F-terms.

We study the necessary and sufficient topological conditions for general Calabi-Yaus to get a non-supersymmetric AdS exponentially large volume minimum of the scalar potential in flux compactifications of IIB string theory. It turns out that string loop corrections play a crucial role to realise exponentially large volume minima for fibration Calabi-Yaus and to stabilise 4-cycles which support chiral matter. The robustness of these results is due to the \'extended no-scale structure\': for arbitrary Calabi-Yaus, the leading contribution of these corrections to the scalar potential is always vanishing. We use the Coleman-Weinberg potential to motivate this cancellation from the viewpoint of low-energy field theory.

An electroweak singlet coupling through the Higgs portal has a natural mass scale $m_Ssim m_h$. In this mass range its annihilation cross section is dominated by proximity to the $W$, $Z$ and Higgs peaks. Analysis of the $gamma$ ray signal from electroweak singlet annihilation in the mass range $80,mathrm{GeV}

It was proposed recently that type IIB orientifold compactifications on CY(3) in the presence of fluxes exhibit an attractor mechanism similar to the one in black hole physics, in other words that minimizing the relevant scalar potential is equivalent to solving a system of attractor equations. So far this conjecture has been verified only numerically. We show by analytical means that the conjectured susy attractor equations do indeed give supersymmetric minima of the relevant scalar potential. Furthermore, we obtain attractor equations for the most general N=1 flux compactifications of type IIA/B string theory, namely compactifications on SU(3)xSU(3) structure spaces.

Proton structure measurements at high $Q^{2}$ performed by the H1 and ZEUS collaborations at the HERA collider, are reviewed. Neutral and charged current deep inelastic scattering cross sections and structure functions are presented. The review also discusses improvements to the parton density measurements using jet cross section data and recent high $Q^{2}$ inclusive cross section measurements.

Theories unifying gravity with other interactions suggest temporal and spatial variation of the fundamental \'constants\' in expanding Universe. The spatial variation can explain fine tuning of the fundamental constants which allows humans (and any life) to appear. We appeared in the area of the Universe where the values of the fundamental constants are consistent with our existence. I present a review of works devoted to the variation of the fine structure constant alpha, strong interaction and fundamental masses (Higgs vacuum). There are some hints for the variation in quasar absorption spectra and Big Bang nucleosynthesis data. A very promising method to search for the variation consists in comparison of different atomic clocks. Huge enhancement of the variation effects happens in transitions between very close atomic, nuclear and molecular energy levels. Large enhancement also happens in nuclear, atomic and molecular collisions near resonances. How changing physical constants may occur? Light scalar fields very naturally appear in modern cosmological models, affecting parameters of the Standard Model (e.g. alpha). Cosmological variations of these scalar fields should occur because of drastic changes of matter composition in Universe: the latest such event is rather recent (about 5 billion years ago), from matter to dark energy domination. Massive bodies can also affect physical constants. The strongest limits are obtained from the measurements of dependence of atomic frequencies on the distance from Sun (the distance varies due to the ellipticity of the Earth\'s orbit).