Fermion localization and resonances on a de Sitter thick brane

Abstract

In C. A. S. Almeida, R. Casana, M. M. Ferreira, Jr., and A. R. Gomes, Phys. Rev. D 79, 125022 (2009), the simplest Yukawa coupling $\ensuremath{\eta}\overline{\ensuremath{\Psi}}\ensuremath{\phi}\ensuremath{\chi}\ensuremath{\Psi}$ was considered for a two-scalar-generated Bloch brane model. Fermionic resonances for both chiralities were obtained, and their appearance is related to branes with internal structure. Inspired on this result, we investigate the localization and resonance spectrum of fermions on a one-scalar-generated de Sitter thick brane with a class of scalar-fermion couplings $\ensuremath{\eta}\overline{\ensuremath{\Psi}}{\ensuremath{\phi}}^{k}\ensuremath{\Psi}$ with positive odd integer $k$. A set of massive fermionic resonances for both chiralities is obtained when provided large coupling constant $\ensuremath{\eta}$. We find that the masses and lifetimes of left and right chiral resonances are almost the same, which demonstrates that it is possible to compose massive Dirac fermions from the left and right chiral resonances. The resonance with lower mass has longer lifetime. For a same set of parameters, the number of resonances increases with $k$ and the lifetime of the lower level resonance for larger $k$ is much longer than the one for smaller $k$.