MARC 主機 00000nam  2200325   4500 
001    AAI3235338 
005    20080111103817.5 
008    080111s2006                        eng d 
020    9780542895753 
035    (UMI)AAI3235338 
040    UMI|cUMI 
100 1  Saltman, Alexander Harry 
245 10 Walking the landscape: The distribution and evolution of 
       string theory vacua 
300    86 p 
500    Source: Dissertation Abstracts International, Volume: 67-
       09, Section: B, page: 5165 
500    Adviser: Eva Silverstein 
502    Thesis (Ph.D.)--Stanford University, 2006 
520    The number of perturbatively stable compactifications of 
       string theory appears to be quite large, even when limited
       to those with a cosmological constant. Although the 
       richness of this "landscape" of vacua may offer solutions 
       to some outstanding problems, notably the cosmological 
       constant problem, it also may dramatically reduce the 
       predictivity of string theory. I demonstrate two classes 
       of vacua that have so far been little explored, but that 
       are quite possibly larger than the more well-known 
       classes. In addition to enumerating possible vacua, it is 
       necessary to study the selection rules that may govern the
       probability of ending up in a particular vacuum starting 
       from a hot, small early universe. To this end, I also 
       discuss certain topology-changing transitions between 
       string compactifications that progress through the 
       condensation of a tachyon, and therefore are essentially 
       irreversible. These transitions have distinct low-energy 
       signatures and suggest that string theory may have a 
       preference for topologically simple compactifications 
590    School code: 0212 
590    DDC 
650  4 Physics, Theory 
650  4 Physics, Elementary Particles and High Energy 
690    0753 
690    0798 
710 2  Stanford University 
773 0  |tDissertation Abstracts International|g67-09B 
856 40 |u