D-brane instantons as gauge instantons in orientifolds of chiral quiver theories

We consider D-branes at orientifold singularities and discuss two properties of the corresponding low energy four-dimensional effective theories which are not shared, generically, by other Calabi-Yau singularities. The first property is that duality cascades are finite and, unlike ordinary ones, do not require an infinite number of degrees of freedom to be UVcompleted. The second is that orientifolds tend to stabilize runaway directions. These two properties can have interesting implications and widen in an intriguing way the variety of gauge theories one can describe using D-branes.

Section: Flavors and Superconformal Phasesmentioning

confidence: 96%

Section: The Cascadementioning

confidence: 99%

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Orientifolds and duality cascades: confinement before the wall

Argurio

Bertolini

2018

“…Equivalently, this corresponds to locating the instanton on the faces of the dimer associated to the fractional branes. This is perhaps not surprising, since D-brane instanton effects in various CY 3-folds can be understood as the IR dynamics of theories with duality cascades generated by fractional branes [55][56][57].…”

Section: Multi-instantons and Complex Deformationsmentioning

confidence: 99%

Bipartite field theories and D-brane instantons

Franco

García-Valdecasas

Uranga

2018

Self Cite

We study D-brane instantons in systems of D3-branes at toric CY 3-fold singularities. The instanton effect can be described as a backreaction modifying the geometry of the mirror configuration, in which the breaking of U (1) symmetries by the instanton translates into the recombination of gauge D-branes, which also directly generates the instanton-induced charged field theory operator. In this paper we describe the D-brane instanton backreaction in terms of a combinatorial operation in the bipartite dimer diagram of the original theory. Interestingly, the resulting theory is a general Bipartite Field Theory (BFT), defined by a bipartite graph tiling a general (possibly higher-genus) Riemann surface. This provides the first string theory realization of such general BFTs. We study the general properties of the resulting theories, including the construction of the higher-dimensional toric diagrams and the interplay between backreaction and Seiberg duality. In cases where the non-perturbative effects relate to complex deformations, we show that the procedure reproduces and explains earlier existing combinatorial recipes. The combinatorial operation and its properties generalize to an operation on the class of general BFTs, even including boundaries, relating BFTs defined on Riemann surfaces of different genus. arXiv:1805.00011v2 [hep-th] 6 Sep 2018 7 The Inverse Problem 43 8 Conclusions 46 -1 -1 Closely related theories were introduced in [22] and studied further in [23].-3 -depiction of the handle attachment surgery which simplifies the discussion of the genus increase. In §4 we describe the computation of the new toric data corresponding to the backreacted BFTs. The change in perfect matchings between the original and final theories is discussed in §4.1, yielding the construction of the new toric diagram in §4.2. A direct construction based on relating new toric coordinates with the bridges identifying formerly different nodes of the original theory is provided in §4.3. These concepts are illustrated in a detailed example in §4.4. In §5 we describe instances of the interplay of instanton backreaction and Seiberg duality: in §5.1, when they are applied to the same dimer face, and in §5.2 when applied to neighboring faces. In §6 we consider the generalization to backreaction of multi-instantons, focusing on cases corresponding to complex deformations of the original CY 3-fold, and recover earlier results in the literature. In §7 we show the non-uniqueness of the inverse problem of reconstructing initial theories for a given final one. We present our concluding remarks in §8. Review of D-brane Instanton Backreaction on D-Branes at SingularitiesIn this section we review some background material on dimer diagrams as tools to describe systems of D3-branes at toric singularities. Subsequently we review the backreaction of instantons in the mirror of these systems, to lay the ground for their novel discussion in the dimer diagram, and the connection with general BFTs.

“…In our phenomenological analysis, we will take into account a non vanishing value of the lepton mixing angle θ 13 , as measured in [71][72][73], assuming the best fit value given in [73]. We will 6 See [51] for a recent paper on D-brane instantons in chiral quiver theories. 7 An alternative mechanism for Baryon Asymmetry of the Universe (BAU) can be envisaged.…”

Section: Jhep02(2016)035mentioning

confidence: 99%

Exotic see-saw mechanism for neutrinos and leptogenesis in a Pati-Salam model

Addazi

Bianchi

Ricciardi

2016

We discuss non-perturbative corrections to the neutrino sector, in the context of a D-brane Pati-Salam-like model, that can be obtained as a simple alternative to SO(10) GUT's in theories with open and unoriented strings. In such D-brane models, exotic stringy instantons can correct the right-handed neutrino mass matrix in a calculable way, thus affecting mass hierarchies and modifying the see-saw mechanism to what we name exotic see-saw. For a wide range of parameters, a compact spectrum of right-handed neutrino masses can occur that gives rise to a predictive scenario for low energy observables. This model also provides a viable mechanism for Baryon Asymmetry in the Universe (BAU) through leptogenesis. Finally, a Majorana mass for the neutron is naturally predicted in the model, leading to potentially testable neutron-antineutron oscillations. Combined measurements in neutrino and neutron-antineutron sectors could provide precious informations on physics at the quantum gravity scale.