**Abstract:**

String phenomenology is a broad area of research. We focus these lectures on Type IIB/F-theory compactifications, as they are a phenomenologically promising scenario for which the N=1 effective action has been studied intensively in the last years.

In the first part we will review recent progress in the study of the phenomenological implications of type IIB string theory focusing on the 4D N=1 supergravity effective action which is obtained as the low-energy limit of compactifications on Calabi-Yau orientifolds. In particular, we will present a brief description of moduli stabilisation and de Sitter vacua in globally consistent Calabi-Yau examples with the presence of semi-realistic chiral D-brane models. Moreover we will discuss supersymmetry breaking and its mediation as well as the role played by moduli in understanding both inflation and the post-inflationary evolution of our Universe (reheating, dark radiation and dark matter).

In the second part, we will introduce F-theory as a strong coupling formulation of Type IIB string theory, which elegantly combines phenomenologically appealing features proper to different corners of the perturbative regime. We will discuss how to fully access the dynamics of F-theory via a chain of dualities from M-theory, and how, in this context, general 7-brane backgrounds are described by the geometry of elliptic fibrations. We will furthermore describe the way to recover open/closed type IIB string physics at weak coupling by constraining the shape of the F-theory compactification. We will finally review the basic ingredients of F-theory phenomenology, especially focusing on the description of fluxes and on their use in the context of GUT model building.

**References:**

For the first part:

- A. Maharana, E. Palti, "Models of Particle Physics from Type IIB String Theory and F-theory: A Review", arXiv:1212.0555
- G. Aldazabal, L. E. Ibanez, F. Quevedo, A.M. Uranga, "D-branes at singularities: A Bottom up approach to the string embedding of the standard model", hep-th/0005067
- M. Rummel, A. Westphal "A sufficient condition for de Sitter vacua in type IIB string theory", arXiv:1107.2115
- M. Cicoli, D. Klevers, S. Krippendorf, C. Mayrhofer, F. Quevedo, R. Valandro "Explicit de Sitter Flux Vacua for Global String Models with Chiral Matter", arXiv:1312.0014
- R. Blumenhagen, J.P.Conlon, S. Krippendorf, S. Moster, F. Quevedo, "SUSY Breaking in Local String/F-Theory Models", arXiv:0906.3297
- C.P. Burgess, M. Cicoli, F. Quevedo, "String Inflation After Planck 2013", arXiv:1306.3512
- M. Cicoli, J. P.Conlon, F. Quevedo, "Dark Radiation in LARGE Volume Models", arXiv:1208.3562
- J. P. Conlon, M. C. D. Marsh, "Searching for a 0.1-1 keV Cosmic Axion Background", arXiv:1305.3603

For the second part:

- C. Vafa, "Evidence for F-theory", hep-th/9602022.
- A. Sen, "F-theory and Orientifolds", hep-th/9605150.
- C. Beasley, J. J. Heckman, and C. Vafa, "GUTs and Exceptional Branes in F-theory - I , II", arXiv: 0802.3391 , 0806.0102.
- R. Donagi and M. Wijnholt, "Breaking GUT Groups in F-theory", arXiv: 0808.2223.
- F. Denef, "Les Houches Lectures on Constructing String Vacua", arXiv: 0803.1194.
- J. J. Heckman, "Particle Physics Implication of F-theory", arXiv: 1001.0577.
- T. Weigand, "Lectures on F-theory compactifications and model building", arXiv: 1009.3497.