Search results for "Orbifold"
showing 6 items of 16 documents
Deforming D-brane models on T6/(Z2×Z2M) orbifolds
2016
We review the stabilisation of complex structure moduli in Type IIA orientifolds, especially on with discrete torsion, via deformations of orbifold singularities. While D6-branes in SO(2N) and USp(2N) models always preserve supersymmetry and thus give rise to flat directions, in an exemplary Pati-Salam model with only U(N) gauge groups ten out of the 15 deformation moduli can be stabilised at the orbifold point.
From stringy particle physics to moduli stabilisation and cosmology
2016
Intersecting D6-branes provide a geometrically intuitive road to stringy particle physics models, where D6-branes stuck at orbifold singularities can lead to the stabilisation of deformation moduli, and the QCD axion can arise from the open string sector in a very constrained way compared to pure field theory. We demonstrate this interplay of different physical features here through an explicit model.
A closer look at mirrors and quotients of Calabi-Yau threefolds
2016
Let X be the toric variety (P1)4 associated with its four-dimensional polytope 1. Denote by X˜ the resolution of the singular Fano variety Xo associated with the dual polytope 1o. Generically, anticanonical sections Y of X and anticanonical sections Y˜ of X˜ are mirror partners in the sense of Batyrev. Our main result is the following: the Hodge-theoretic mirror of the quotient Z associated to a maximal admissible pair (Y, G) in X is not a quotient Z˜ associated to an admissible pair in X˜ . Nevertheless, it is possible to construct a mirror orbifold for Z by means of a quotient of a suitable Y˜. Its crepant resolution is a Calabi-Yau threefold with Hodge numbers (8, 4). Instead, if we star…
Flavour and CP predictions from orbifold compactification
2020
We propose a theory for fermion masses and mixings in which an $A_4$ family symmetry arises naturally from a six-dimensional spacetime after orbifold compactification. The flavour symmetry leads to the successful "golden" quark-lepton unification formula. The model reproduces oscillation parameters with good precision, giving sharp predictions for the CP violating phases of quarks and leptons, in particular $\delta^\ell \simeq +268 ^\circ$. The effective neutrinoless double-beta decay mass parameter is also sharply predicted as $\langle m_{\beta\beta}\rangle \simeq 2.65\ meV$.
Finite quotients of the Picard group and related hyperbolic tetrahedral and Bianchi groups
2001
There is an extensive literature on the fi{}nite index subgroups and the fi{}nite quotient groups of the Picard group $PSL\left(2,\mathbb{Z}\mid i\mid\right)$. The main result of the present paper is the classifi{}cation of all linear fractional groups $PSL\left(2,p^{m}\right)$ which occur as fi{}nite quotients of the Picard group. We classify also the fi{}nite quotients of linear fractional type of various related hyperbolic tetrahedral groups which uniformize the cusped orientable hyperbolic 3-orbifolds of minimal volumes. Also these cusped tetrahedral groups are of Bianchi type, that is of the form $PSL\left(2,\mathbb{Z}\mid\omega\mid\right)$ or $PGL\left(2,\mathbb{Z}\mid\omega\mid\right…
On the classification of Kim and Kostrikin manifolds
2006
International audience; We completely classify the topological and geometric structures of some series of closed connected orientable 3-manifolds introduced by Kim and Kostrikin in [20, 21] as quotient spaces of certain polyhedral 3-cells by pairwise identifications of their boundary faces. Then we study further classes of closed orientable 3-manifolds arising from similar polyhedral schemata, and describe their topological properties.