# String Phenomenology 2015

# Wednesday Parallel Sessions

Wednesday 10th |
Blue Room |
Red Room |
Grey Room 1 |

Chair | Pedro |
Savelli |
Anderson |

16:30 | Retolaza |
Kapfer |
Sharpe |

16:45 | Valenzuela |
Baume |
Lee |

17:00 | Landete |
Till |
Gray |

17:15 | Mangat |
Lin |
Gao |

17:30 | Rompineve |
Oehlmann |
Berasaluce-González |

17:45 | Plauschinn |
Mayorga |
Piazzalunga |

18:00 | Fuchs |
Addazi |
Hayashi |

Back to overview schedule of all parallel sessions

**Addazi**

**,**Neutron-Antineutron transitions from Exotic Instantons: how fast they can be and further implications,
A Neutron-Antineutron oscillation can be generated by non-perturbative stringy effects. In particular, "Exotic Instantons" could generate 6 quarks effective operators (\Delta B=2), beyond the Standard Model. These effects are calculable and controllable in a large class models with intersecting D-branes models. Contrary to Explicitly R-parity breaking MSSM, and the largest part of GUT, n-\bar{n} transition does not lead to a proton destabilization in a comparable time. So, an intriguing question for phenomenology is: how fast might n-\bar{n} transitions be? We show that such a process can be very fast in comparison with other Baryon and Lepton violating transitions, such as proton decays of neutrinoless-double-beta-decays. Current best limits on n-\bar{n} are surprisingly low, and the next generation of experiments promise to enhance these of two orders in transition time! Further phenomenological implications are also discussed, in susy SM-like and susy PS-like cases. In particular, a lot of implications for LHC, FCNC, Dark Matter issues, Ultra Cold Neutron physics and Ultra High Energy Cosmic Rays are also considered. This talk is connected to the one of Massimo Bianchi.

**Baume**

*, On E8 and F-Theory GUT,*

We study correlations between the massless field spectra of F-theory fibrations supporting an SU(5) gauge symmetry extended by Abelian symmetries and the spectra that arise from the group E8. When extended in a specific way, E8 may have a role to play in controlling the possible matter spectra in F-theory.

**Berasaluce-González**

*,On the physical realization of Seiberg dual phases in branes at singularities,*

While in the case of non-chiral theories there is a correspondence between Seiberg duals and supersymmetric configurations of branes, this is not necesarily true in the chiral case. A natural conjecture one can think is that such a map exists when the two dual theories are also toric duals. We address this possibility by first computing the quiver locus of C^3/(Z3xZ3), and using this as starting point, we compute the quiver locus of theories that are obtained from it via partial resolutions of the singularity.

**Fuchs**

*, A Flux Scaling Scenario and Plateau Inflation,*

A high tensor to scalar ratio favors polynomial mass hierarchies instead of exponential ones. This is possible in string theory if you also consider non-geometric fluxes. They induce a polynomial superpotential which makes it possible to stabilize all moduli at tree level. The phenomenology of such models is presented and it is shown how to use them for axion monodromy inflation. It is explained how the tensor to scalar ratio depends on the mass difference between the inflaton and the other moduli. If there is no difference we get a plateau like inflationary potential.

**Gao**

*, Sections and multiple fibrations in CICY 3-folds,*

I will present a short survey of multi-fiberation in Complete Intersection Calabi-Yau threefold, its construction and numerical statistic.

I discuss a large class of explicit constructions of Calabi-Yau which can be described as multiple different elliptic fibrations. Using this data set I give a cartography of various dualities in F-theory, M-theory and the Heterotic string.

We extend the investigation of the recently introduced class Sk of 4d N=1 SCFTs, by considering a large family of quiver gauge theories within it. These theories admit a realization in terms of Zk orbifolds of Type IIA configurations of D4-branes stretched among relatively rotated sets of NS5-branes. This fact permits a systematic investigation of the full family, which exhibits new features such as non-trivial anomalous dimensions differing from free field values and novel ways of gluing theories. We relate these ingredients to properties of compactifications of the 6d (1,0) superconformal T^k_N theories on spheres with different kinds of punctures.

**Kapfer**

*, The Arithmetic of Elliptic curves in F-theory,*

Elliptic curves show rich arithmetic structures. We investigate their manifestation in F-theory compactifications on elliptically-fibered Calabi-Yau manifolds. Special focus is put on the Mordell-Weil group, Tate-Shafarevich group and the group of exceptional divisors.

**Landete**

*, Large field inflation from D-branes,*

**Lee**

*, Generalized CICY three-folds,*

A methodology for exploring a new class of complete intersection Calabi-Yau three-folds is discussed and an example presented. The Calabi-Yau three-folds in this class would not only provide more string vacua for string phenomenology but also enhance the understanding of mirror pairs.

**Lin**

*, F-theory Standard Model with chiral Spectra,*

I will present F-theory compactifications that lead to SU(3)xSU(2)xU(1)xU(1) gauge group and various matter fields. To generate a chiral spectrum G4-flux needs to be included. I will present a systematic way to determine all possible vertical fluxes and the chiral spectra one can obtain this way.

We discuss the realisation of large field inflation in the framework of F-term axion monodromy inflation and show how fine-tuning requirements arise to make these scenarios work. Moreover, we provide estimations of the severeness of this tuning in the flux landscape of type IIB string theory.

**Mayorga**

*, Three family models of particle physics from global F-theory compactifications,*

We construct four-dimensional, globally consistent F-theory models with three chiral generations, whose gauge group and matter representations coincide with those of the Minimal Supersymmetric Standard Model, the Pati-Salam Model and the Trinification Model. These models result from compactification on toric hypersurface fibrations X with the choice of base P3. We observe that the F-theory conditions on the G4-flux restrict the number of families to be at least three. We comment on the phenomenology of the models, and for Pati-Salam and Trinification models discuss the Higgsing to the Standard Model. A central point of this work is the construction of globally consistent G4-flux. For this purpose we compute the vertical cohomology H(2,2)^V in each case and solve the conditions imposed by matching the M- and F-theoretical 3D Chern-Simons terms. We explicitly check that the expressions found for the G4-flux allow for a cancelation of D3-brane tadpoles. We also use the integrality of 3D Chern-Simons terms to ensure that our G4-flux solutions are adequately quantized.

**Oehlmann**

*, The Toric Network of F-theory fibrations,*

We are studying F-theory fibrations in six dimensions where the fiber is realized as a hypersurface in the 16 classic 2D toric varieties. We find that all resulting theories are interconnected and have features such as quotient groups, non-toric U(1)'s and discrete groups. Moreover the overall structure of the resulting network of theories suggests a connection between Mordell-Weil torsion and the Tate-Shafarevich group via Mirror-Symmetry in the fiber.

**Piazzalunga**

*, Nekrasov partition function for the real topological string*

After briefly introducing the real topological string, namely tadpole cancelling O4/D4 configurations as proposed by J. Walcher, and its M-theory lift, I discuss the gauge theory dual in terms of appropriate shift of Nekrasov instanton partition function: in the geometric engineering setup where gravity decouples, this is expected to match local CY computations with the real topological vertex, up to some peculiar sign choices which I explain.

**Plauschinn**

*, A flux-scaling scenario for axion inflation in string theory,*

We present a scenario for realizing axion inflation in string theory. This scenario utilizes geometric as well as non-geometric fluxes to stabilize moduli at tree level in type IIB string theory. A light inflaton candidate can be incorporated by arranging for a hierarchy in the fluxes, which can be achieved by a certain scaling.

**Retolaza**

*, Bifid Throats for Axion Monodromy Inflation,*

I construct a local toric CY geometry providing a "bifid throat" for 5-brane axion monodromy. A bifid throat is a throat that splits into two daughter throats in the IR, containing a homologous 2-cycle family reaching down into each daughter throat. As the geometry is toric, it allows for a holographic description in terms of a dual gauge theory including D3-branes and fractional 5-branes at the singularity of our setup. Using the holographic description I address the effect of 5-brane-antibrane pair backreaction including the warping effects. This leads to the size of the backreaction being small and controllable after imposing proper normalization of the inflaton potential and hence the warping scales.

**Rompineve**

*, F-term axion monodromy inflation with complex structure moduli,*

We focus on the backreaction of complex structure moduli in axion monodromy inflation. In our setting, the shift symmetry comes from a partial large complex structure limit of the underlying type IIB orientifold or F-theory fourfold. The coefficient of the inflaton term in the superpotential has to be tuned small to avoid conflict with Kahler moduli stabilisation. To allow such a tuning, this coefficient necessarily depends on further complex structure moduli. At large values of the inflaton field, these moduli are then in danger of backreacting too strongly. To avoid this, further tunings are necessary. We discuss how to realise them in a F-theory fourfold setting and study the resulting scalar potential for the inflaton field.

**Sharpe**

*, Recent developments in 2d (0,2) theories,*

In this short talk I will summarize recent developments in 2d (0,2) theories, focusing on recent work in dualities and trialities.

**Till**

*, G4 fluxes*

*in F-theory with*

*discrete selection rules*

We study flux configurations in F-theory models on genus one fibrations with extra non-abelian singularities. We perform a systematic study of the possible flux solutions, and check for consistency via the conifold transition to a model with an extra U(1). The theory is shown to be free of SU(5) anomalies, and we comment on the quantization condition.

**Valenzuela**

*, Higgs-otic inflation in String Theory,*

Higgs-otic inflation refers to theories in which the inflaton is a complex scalar giving rise to gauge symmetry breaking, while attaining large field inflation. The most obvious and natural candidate for that is the SM Higgs field itself. We provide a successful embedding of the model in string theory by identifying the Higgs fields with a D-brane position. The inflaton potential is then given by a DBI+CS D-brane action yielding an approximate linear behaviour at large field. We show that the potential is protected from large trans-Planckian corrections by the modular symmetries of string theory.

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© 2012-2013 Institute for Theoretical Physics UAM - CSIC

© 2012-2013 Institute for Theoretical Physics UAM - CSIC