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SUMMARY:Supergravity wastelands and string theory moorlands – theoretica
 l challenges in accommodating an accelerated expansion - David Marsh\, DAM
 TP
DTSTART:20151204T130000Z
DTEND:20151204T140000Z
UID:TALK61742@talks.cam.ac.uk
CONTACT:43345
DESCRIPTION:There are many compactifications of string theory and\, conseq
 uently\, there is a large set of four-dimensional effective theories arisi
 ng in its low-energy limits. Can cosmology guide the search for observatio
 nally viable vacua? I will review how vacua that are consistent with the o
 bservation of an accelerated expansion can be expected to be very rare in 
 ‘random’ supergravity theories without additional structures\, and how
  this may be used to find corners of the ‘landscape’ with more favoura
 ble properties. I will show that in some regions of the moduli space\, gen
 eral flux compactifications of type IIB string theory and F-theory exhibit
  universal spectra that are independent of the geometry\, topology or flux
  threading the compactification manifold. Moreover\, these spectra are in 
 stark contrast with the expectations from random ensembles of supergravity
  theories. Finally\, I will show how de Sitter vacua appear with comparati
 vely little tuning by spontaneous supersymmetry breaking in compactificati
 ons with a  weakly broken “no-scale” symmetry.
LOCATION:Pavilion B Potter Room (B1.19)
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