Hierarchies from extra dimensions

by Prof. Mitsuru Kakizaki (Toyama U.)

Tuesday 12 Aug 2025, 14:00 → 15:30 Asia/Seoul

Room 1423 (KIAS)

Title: Hierarchies from extra dimensions

Speaker: Prof. Mitsuru Kakizaki (Toyama U.)

Abstract: We explore how field localization in extra-dimensional spacetime can provide natural explanations for several fundamental hierarchies in particle physics, such as fermion mass hierarchies and Yukawa coupling structures, without relying on additional flavor symmetries. By introducing domain-wall backgrounds and adjoint Higgs fields in supersymmetric grand unified theories, we show how translational invariance and GUT symmetries can be broken simultaneously, leading to realistic mass spectra and addressing the doublet–triplet splitting problem and proton decay constraints. We further apply this framework to two-Higgs-doublet models in flat extra dimensions, demonstrating that various types of Yukawa couplings can be naturally realized through geometric configurations. This mechanism offers a symmetry-independent and phenomenologically viable approach toward understanding the origin of mass and coupling hierarchies in extensions of the Standard Model.