Selfgravitating SU(5) Higgs domain walls as a braneworlds
Abstract
Five-dimensional domain walls in gauged SU(5) generate a position-dependent symmetry breaking pattern along the additional dimension. We analize the perturbative stability and the 4D spectrum of these walls in the self-gravitating case, in terms of diffeomorphism- and Lie algebra gauge-invariant field fluctuations. We show that tachyonic modes are absent, ensuring perturbative stability. As expected, gravitational tensor and vector fluctuations behave like its counterparts in the standard Z2 domain walls. All the Lie algebra valued fluctuations exhibit towers of 4D massive modes which propagate in the bulk, with a continuous spectrum starting from zero. All the would-be 4D Nambu-Goldstone fields, which are gravitationally trapped in the case of a global symmetry, are non-trivially absent. However we find no localizable 4D gauge bosons, either massless or massive. Instead, quasi-localizable discrete 4D massive modes for the gauge field fluctuations are found, along the spontaneously broken directions.