de Sitter vacua in the string landscape

Rigid nongeometric orientifolds and the swampland

“…see [80,114], where = 1 2 c 2 and |η| = c , and these are needed to be sufficiently smaller than one for having the slow-roll inflation. In the meanwhile, there have been a surge in related studies in connection with this conjecture [102][103][104][105][106][107][108][109][110][111][112][115][116][117][118][119][120][121][122][123][124][125][126]; see [127] also for a recent review. The swampland conjecture [98] has been also found to be in close connections with the allowed inflaton field range in a trustworthy effective field theory description as it has been argued that massive tower of states can get excited after a certain limit to the inflaton excursions [128][129][130][131][132][133][134][135][136][137][138][139][140][141][142].…”

Kalb-Ramond backgrounds in α′-complete cosmology

“…The α corrections implies a nonlinear theory for b(t), and so it could be that its flux alone could stabilize the volume moduli. However, further investigation is necessary since a full stabilization mechanism would require us to consider a much more general metric than the one considered in the duality invariant setup (see [35,36], and references therein for a discussion on time-dependent fluxes in moduli stabilization).…”

Scale-invariant cosmology in de Sitter gauge theory

“…In the more mainstream context of string theory, the existence of negative energy vacua seems to be not only a generic prediction in the landscape of myriad universes, but a requirement for the consistent definition of an Smatrix, and it has proven quite a challenge to find ways that may lead to positive vacuum energies compatible with the one observed universe [49,50]. Previous attempts at realising a non-singular anti-dS to dS transition have resorted to rather complicated mechanisms requiring various new indgredients for their realisation [51,52].…”