Abstract
In this work we show that universal gauge vector fields can be localized on the recently proposed 5D thick tachyonic braneworld which involves a de Sitter cosmological background induced on the 3-brane. Namely, by performing a suitable decomposition of the vector field, the resulting 4D effective action corresponds to a massive gauge field, while the profile along the extra dimension obeys a Schroedinger-like equation with a Poeschl-Teller potential. It turns out that the massless zero mode of the gauge field is bound to the expanding 3-brane and allows us to recover the standard 4D electromagnetic phenomena of our world. Moreover, this zero mode is separated from the continuum of Kaluza-Klein (KK) modes by a mass gap determined by the scale of the expansion parameter. We also were able to analytically solve the corresponding Schroedinger-like equation for arbitrary mass, showing that KK massive modes asymptotically behave like plane waves as expected.
Highlights
An interesting issue within the braneworld paradigm is related to the question of whether bulk matter fields can be confined to the brane by a natural mechanism
We have shown that gauge field localization in the de Sitter thick braneworld generated by gravity coupled to a tachyonic scalar field is feasible since the normalizable vector zero mode can be localized on the brane
The spectrum consists of a massless zero mode and a series of continuous massive KK gauge modes separated by a mass gap from the massless one, as happens in the KK spectrum of the metric fluctuations [40]
Summary
An interesting issue within the braneworld paradigm is related to the question of whether bulk matter fields can be confined to the brane by a natural mechanism. In this paper we use a recently proposed thick tachyonic braneworld configuration with a de Sitter metric induced on the brane and a decaying warp factor that enables the localization of 4D gravity [40], and show that universal gauge. The full solution corresponds to a non-trivial 5D configuration that describes a thick braneworld supported by a real tachyonic scalar field in which the induced metric on the 3-brane is described by a de Sitter 4D cosmological background. It is worth noticing that this invariant is positive definite and vanishes asymptotically, yielding an asymptotically 5D Minkowski spacetime This is a very peculiar and novel property of the braneworld configuration under consideration since, usually, in the absence of matter a negative cosmological constant 5 leads to an asymptotically Ad S5 spacetime. From (1) it is clear that both the cosmological constant 5 and the self-interaction potentV (T ) contribute to the asymptotically vanishing overall effective cosmological constant of the 5D spacetime of the tachyonic braneworld
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