Search Talks

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.

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).

The Fermilab Tevatron is currently the highest energy particle collider in the world and is host of the CDF and DZero experiments. Measurements performed by these two international collaborations have significantly improved our knowledge of subatomic physics and helped further constrain different scenarios of physics beyond the Standard Model. A summary of some of the latest results and future experimental goals of the Tevatron\'s experiments will be presented.

Inflation is generically a never ending process, with new \'pocket universes\' constantly being formed. All possible events will happen an infinite number of times in such an eternally inflating universe. Unless we learn how to compare these infinities, we will not be able to make any predictions at all. I will discuss some proposed approaches to this \'measure problem\'.