MARC 主機 00000nam  2200313   4500 
001    AAI3251267 
005    20080111103839.5 
008    080111s2007                        eng d 
035    (UMI)AAI3251267 
040    UMI|cUMI 
100 1  Ernebjerg, Morten 
245 10 Field theory methods in two-dimensional and heterotic 
       string theories 
300    151 p 
500    Source: Dissertation Abstracts International, Volume: 68-
       02, Section: B, page: 1039 
500    Adviser: Andrew Strominger 
502    Thesis (Ph.D.)--Harvard University, 2007 
520    This thesis has three parts. In the first, we study the 
       Das-Jevicki collective field description of arbitrary 
       classical solutions in the c = 1 matrix model, which are 
       believed to describe nontrivial spacetime backgrounds in 
       2D string theory. Our analysis naturally includes the case
       of a Fermi droplet cosmology. We cast the droplet 
       collective field theory in standard coordinates and 
       comment on the form of the interactions 
520    In the second part, we prove the existence of topological 
       rings in (0, 2) theories containing non-anomalous left-
       moving U(1) currents by which they may be twisted. While 
       the twisted models are not topological, their ground 
       operators form a ring under non-singular OPE which reduces
       to the (a,c) or (c,c) ring at (2, 2) points and define a 
       quantum sheaf cohomology. In the special case of Calabi-
       Yau compactifications, these rings are shown to exist 
       globally on the moduli space in many cases 
520    In the third part, we construct worldsheet descriptions of
       heterotic flux vacua as the IR limits of   N  = 2 gauge 
       theories. Spacetime torsion is incorporated via a 2D Green
       -Schwarz mechanism in which a doublet of axions cancels a 
       one-loop gauge anomaly. Manifest (0, 2) supersymmetry and 
       the compactness of the gauge theory instanton moduli space
       suggest that these models, which include Fu-Yau models, 
       are stable against worldsheet instantons 
590    School code: 0084 
590    DDC 
650  4 Physics, Elementary Particles and High Energy 
690    0798 
710 2  Harvard University 
773 0  |tDissertation Abstracts International|g68-02B 
856 40 |u