Massless spectra and gauge couplings at one-loop on non-factorisable toroidal orientifolds

Abstract

So-called 'non-factorisable' toroidal orbifolds can be rewritten in a factorised form as a product of three two-tori by imposing an additional shift symmetry. This finding of Blaszczyk et al.[1] provides a new avenue to Conformal Field Theory methods, by which the vector-like massless matter spectrum -and thereby the type of gauge group enhancement on orientifold invariant fractional D6-branes -and the one-loop corrections to the gauge couplings in Type IIA orientifold theories can be computed in addition to the well-established chiral matter spectrum derived from topological intersection numbers among threecycles. We demonstrate this framework for the Z 4 × ΩR orientifolds on the A 3 × A 1 × B 2 -type torus. As observed before for factorisable backgrounds, also here the one-loop correction can drive the gauge groups to stronger coupling as demonstrated by means of a four-generation Pati-Salam example. arXiv:1709.07866v3 [hep-th]

On classical de Sitter and Minkowski solutions with intersecting branes

“…In addition, we will look here for more involved solutions than those on a torus orbifold (see e.g. [29][30][31] for attempts of model building in this direction), allowing for fluxes and curved manifolds. Such a setup would help stabilizing closed string moduli, on top of the effects described in [32], so it should be interesting for such constructions.…”

Yukawa couplings from magnetized D-brane models on non-factorisable tori

“…Similar to (69), the sum over λ can be replaced by an enlarged domain of integration over y 2 , y 4 , y 6 C dy 2 dy 4 dy 6…”

“…Usually toroidal constructions are performed on so called factorisable six-tori consisting of three mutually orthogonal two-tori. Generalisations to non factorisable tori are studied in [60][61][62][63][64][65][66][67][68][69]. In particular in [67] Yukawa couplings for intersecting branes on non factorisable six-tori have been computed.…”

Phases of inflation

“…[19][20][21] and for recent attempts in Type IIA see e.g. [22][23][24][25][26]. Compactifications including D-branes with chiral gauge theories are characterized by additional four-dimensional mixing effects among multiple axions, such that their rich structure allows for parametrically large effective axion decay constants [27,28], an indispensable first step towards natural inflation.…”