Theories with Large Hierarchy of Scales

Author(s)

Nayara Fonseca de Sá

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Física (IF/SBI)
• Defense date: 2016-08-26

Examining board members

Gustavo Alberto Burdman; Eduardo Pontón Bayona; Oscar Jose Pinto Eboli; Gero Arthur Hubertus Thilo Freiherr von Gersdorff; Rogério Rosenfeld

• Advisor: Gustavo Alberto Burdman

Abstract

this thesis we explore a class of N-site models that were developed to generate large-scale hierarchies. Using the dimensional deconstruction approach and appropriate matchings, these purely four-dimensional theories coincide with AdS5 models in the continuum limit, which corresponds to the limit with a large number of gauge groups. On the other hand, in the coarse lattice limit such theories have very distinct couplings of the excited states to zero mode fields compared with AdS5 constructions, resulting in a rich phenomenology to be explored at the Large Hadron Collider (LHC). The Standard Model (SM) hierarchy problem is solved if the Higgs field is infrared-localized as in Randall-Sundrum scenarios. The SM fermion mass hierarchy and mixings are obtained by different localizations of zero mode fermions in the theory space. This framework is employed to tackle the electroweak hierarchy problem from a new perspective. We show that an effective few site description of a warped extra dimension can implement the recently introduced relaxion models, which are a new alternative to explain the radiative stability of the SM scalar sector through the cosmological relaxation mechanism. These models require very large field excursions, which are difficult to generate in a consistent ultraviolet completion and to reconcile with the compact field space of the relaxion. We propose an N-site model that naturally generates the large decay constant needed to address these problems. In our model, the mass matrix of the pseudo-Nambu-Goldstone Bosons (pNGBs), whose zero mode plays the role of the relaxion field, is identical to the one obtained for a pNGBWilson line in the deconstruction of AdS5. (AU)

• FAPESP's process: 11/10047-9 - Theories with Large Hierarchies: The Origin of Electroweak Scale and Fermion Masses
• Grantee: Nayara Fonseca de Sá
• Support Opportunities: Scholarships in Brazil - Doctorate