Lessons From The Landscape Of Six Dimensional Supergravity Theories

Lessons from the Landscape of Six-dimensional Supergravity Theories

Comparing the set of supergravity theories allowed by low-energy consistency conditions with the set of string vacua provides useful insights into quantum gravity and string theory. In fact, such a "landscape analysis" for ten-dimensional supergravity theories was at the core of the exciting series of developments that is now referred to as the first superstring revolution. In this thesis, we discuss the lessons we learn about quantum supergravity and string theory by carrying out such an analysis for the space of six-dimensional supergravity theories with minimal supersymmetry. We first review six-dimensional supergravity theories and explain why the space of these theories is an ideal place to carry out the landscape analysis. We then describe how anomaly constraints bound the space of consistent theories, i.e., we map the space of theories T that satisfy known low-energy consistency conditions. We then go on to describe string constructions that give six-dimensional string vacua with minimal supersymmetry, i.e., we map the space of theories S c T that come from string vacua. Finally, we compare the space of theories T and S and explore its implications. We first find that there is a large discrepancy between T and S. Among the set T - S, we identify some theories that are potentially new string vacua, but also identify many theories that cannot be embedded in any known string vacua. These theories may potentially be ruled out by yet undiscovered low energy constraints. Understanding these theories is an important step in addressing the question of string universality in six dimensions. We also find some surprising equalities that hold for Calabi-Yau threefolds that follow from demanding that F-theory string vacua should be consistent.

Eleventh Marcel Grossmann Meeting, The: On Recent Developments In Theoretical And Experimental General Relativity, Gravitation And Relativistic Field Theories (In 3 Volumes) - Proceedings Of The Mg11 Meeting On General Relativity

The Marcel Grossmann Meetings are three-yearly forums that meet to discuss recent advances in gravitation, general relativity and relativistic field theories, emphasizing their mathematical foundations, physical predictions and experimental tests. These meetings aim to facilitate the exchange of ideas among scientists, to deepen our understanding of space-time structures, and to review the status of ongoing experiments and observations testing Einstein's theory of gravitation either from ground or space-based experiments. Since the first meeting in 1975 in Trieste, Italy, which was established by Remo Ruffini and Abdus Salam, the range of topics presented at these meetings has gradually widened to accommodate issues of major scientific interest, and attendance has grown to attract more than 900 participants from over 80 countries.This proceedings volume of the eleventh meeting in the series, held in Berlin in 2006, highlights and records the developments and applications of Einstein's theory in diverse areas ranging from fundamental field theories to particle physics, astrophysics and cosmology, made possible by unprecedented technological developments in experimental and observational techniques from space, ground and underground observatories. It provides a broad sampling of the current work in the field, especially relativistic astrophysics, including many reviews by leading figures in the research community.

Proceedings of the Eleventh Marcel Grossmann Meeting on General Relativity