**Strings at the LHC and in the Early Universe**

**Coordinators:** Ralph Blumenhagen, Mirjam Cvetič, Paul G. Langacker, Herman Louis Verlinde

**Scientific Advisors:** Eva Silverstein, Washington Taylor

In the next few years the Large Hadron Collider (LHC) at CERN will for the first time probe physics at energy scales more than an order of magnitude beyond that of the Standard Model. This experiment will explore an energy regime of particle physics where phenomena such as supersymmetry and Grand Unified Theories may become relevant. Certainly, the LHC should shed light on the mechanism of electroweak symmetry breaking and may discover the first fundamental scalar particle seen in nature. Currently, although we have a myriad of proposals for how physics behaves beyond the Standard Model, we have little theoretical guidance as to which of the many possibilities is realized in nature. String theory provides a theoretical arena in which different compactifications, or vacua, of the theory realize many of these different possibilities for beyond-the-standard-model physics. Indeed, many of the ideas currently used in so-called “model building” have their origins in string theory. Recent developments in string theory at the interface with particle physics have led to an improved understanding of at least some part of the set of possibilities for observable physics which can be realized in string theory. The advent of the LHC provides a unique opportunity to make a concentrated attempt to relate observable phenomena to structures found in string vacua, and to find concrete ways in which string theory may have predictions or constraints for observable physics.

Recent work in the study of string vacua has also led to substantial progress in understanding how observable cosmology can be reproduced in string models. While recent experimental evidence favors primordial inflation, it has proven surprisingly challenging to construct large classes of string models with this property. Moreover, with the launching of the PLANCK satellite, it will hopefully be possible to measure gravity waves from the early universe. The measurement of the primordial tensor fluctuation offers an exciting prospect for testing or constraining string models based on cosmological observations.

The aim of the proposed workshop is to bring together world experts working at the interfaces of string theory, particle physics and cosmology. We will focus, on the one hand, on advancing techniques and new physics insights that string theory can bring to particle physics and cosmology, and, on the other hand, on what new data from the LHC and cosmological observations can say about the space of vacuum possibilities realized in string theory. Topics of interest will include recent advances in the non-perturbative study of string vacuum solutions, features of supersymmetry breaking scenarios and new developments in string cosmology.