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SUMMARY:Holography and the self-tuning of the cosmological constant - Elia
 s Kiritsis\, APC Paris and University of Crete
DTSTART:20171025T131500Z
DTEND:20171025T141500Z
UID:TALK81151@talks.cam.ac.uk
CONTACT:David Marsh
DESCRIPTION:We propose a brane-world setup based on gauge/gravity duality 
 in which the four-dimensional cosmological constant is set to zero by a dy
 namical self-adjustment mechanism. The bulk contains Einstein gravity and 
 a scalar field. We study holographic RG flow solutions\, with the standard
  model brane separating an infinite volume UV region and an IR region of f
 inite volume. For generic values of the brane vacuum energy\, regular solu
 tions exist such that the four-dimensional brane is flat. Its position in 
 the bulk is determined dynamically by the junction conditions. Analysis of
  linear fluctuations shows that a regime of 4-dimensional gravity is possi
 ble at large distances\, due to the presence of an induced gravity term. T
 he graviton acquires an effective mass\, and a five-dimensional regime may
   exist at large and/or small scales. We show that\, for a broad choice of
  bulk potentials\, flat-brane solutions are manifestly stable and free of 
 ghosts. We compute the scalar contribution to the force between brane-loca
 lized sources and show that\, in certain models\, the vDVZ discontinuity i
 s absent and the effective interaction at short distances is mediated by t
 wo transverse graviton helicities.
LOCATION:MR2\, Centre for Mathematical Sciences
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