Recent Developments in the Landscape

String theory is the leading candidate for a theory unifying all the laws of nature including gravity. Over the last few years, evidence has been found that the theory has a vast set of solutions, sometimes called the landscape, each of which makes different predictions for the laws of nature. We discuss recent progress in understanding the landscape and its implications, for testing string theory and on a philosophical level.

Towards Realistic Stringy Models of Particle Physics and Cosmology

String phenomenology is the interplay between string theory -- our leading candidate for a unified theory of particle physics and gravity -- and the observable phenomena of modern particle physics and cosmology. As such, it provides the means by which ideas of string theory can have an impact on current and upcoming experiments. In this talk, I will provide a non-technical survey of the basic ideas of string theory, and I will highlight the role that string phenomenology plays in guiding present and future theoretical developments. I will give examples of how string theory suggest new and unconventional approaches for tackling some presently unsolved puzzles, and conversely, how advances in high energy physics and cosmological measurements provide novel ways of probing string theory experimentally.

Getting ready for the LHC

Starting in less than two years from now, particle physics will enter a new regime in terms of energies and luminosities, thanks to the Large Hadron Collider (LHC) at CERN and its experiments. In this talk I will first report on the status of the preparations, both for the machine and the detectors. Then I will describe the start-up scenarios and the very early physics which we expect to study.

Precision Measurement of Gravity at Micrometer Scale using Ultracold Atoms

New quantum devices based on ultracold atoms show unprecedented features in terms of sensitivity, accuracy, and reduced size enabling new experiments and tests of fundamental physics. They are used for precision inertial sensors, to measure fundamental constants, and testing relativity. The extremely small size of atomic sensors enables precision measurements of forces at micrometer scale. This is a challenge in physics for studies of surfaces, Casimir effect, and searches for deviations from Newtonian gravity predicted by theories beyond the standard model. Experiments we are performing using atom interferometry to determine the gravitational constant G and test Newtonian gravitational law at micrometric distances will be presented.

Critical Solitons in Gauge Theories <-> Strings/D Branes/ Dualities

String theory which emerged from dual hadronic models in the late 1960s and 70s, elevated to the theory of everything" in the 1980s and early 90s, seemingly entered a return-to-roots" stage. Results and techniques of string/D-brane theory, being applied to field theories have generated numerous predictions of various degree of relevance for gauge theories. If the latter are, in a sense, dual to string/D-brane theory --- as is generally believed to be the case ---the gauge theories must support domain walls (of the D-brane type). In addition, string/D-brane theory teaches us that a fundamental string that starts on a confined quark, can end on such a domain wall. These features, being established, shed light on regularities inherent to QCD. The task of finding solutions to down- to-earth" problems of QCD and other gauge theories by using ideas from string/D-brane theory is currently recognized by many as a critical goal. On the other hand, insights and hints obtained from field theory are likely to fertilize the internal logic of development of string theory. This is a two way street which I will try to review.