Massive scalar states localized on a de Sitter brane

In a brane (domain wall) scenario with an infinite extra dimension and localized gravity, bulk fermions and scalars often have bound states with zero 4-dimensional mass. In this way massless matter residing on the brane may be obtained. We consider what happens when one tries to introduce small, but non-vanishing mass to these matter fields. We find that the discrete zero modes turn into quasi-localized states with finite 4-dimensional mass and finite width. The latter is due...

We propose new braneworld models arising from a scalar field in the bulk. In these examples, the induced on--brane line element is de Sitter (or anti de Sitter) and the bulk (five dimensional) Einstein equations can be exactly solved to obtain warped spacetimes. The solutions thus derived are single and two-brane models -- one with {\em thin} branes while the other one of the {\em thick} variety. The field profiles and the potentials are obtained and analysed for each case. W...

We consider a single brane embedded in five dimensions with vanishing and positive bulk cosmological constant. In this setup, the existence of $dS_{4}$ brane is allowed. We explore the gravitational fluctuations on the brane, and we point out that the usual four-dimensional gravity can be reproduced by a normalizable zero mode and that the continuous massive modes are separated by a mass gap from zero mode. We derive the relation among the cosmological constant in the brane, ...

We construct an explicit model to describe fermions confined on a four dimensional brane embedded in a five dimensional anti-de Sitter spacetime. We extend previous works to accommodate massive bound states on the brane and exhibit the transverse structure of the fermionic fields. We estimate analytically and calculate numerically the fermion mass spectrum on the brane, which we show to be discrete. The confinement life-time of the bound states is evaluated, and it is shown t...

In this paper, we consider a general coupling mechanism between the kinetic term and the background spacetime, in which a coupling function $F(R)$ is introduced into the kinetic term of the five-dimensional scalar field. Based on this scenario, we investigate the localization of scalar fields in three specific braneworld models: the Minkowski brane, the de Sitter brane, and the Anti-de Sitter brane. For each case, different types of the effective potentials can be achieved de...

Braneworld models may yield interesting effects ranging from high-energy physics to cosmology, or even some low-energy physics. Their mode structure modifies standard results in these physical realms that can be tested and used to set bounds on the models parameters. Now, to define braneworld deviations from standard 4D physics, a notion of matter and gravity localization on the brane is crucial. In this work we investigate the localization of universal massive scalar fields ...

We consider the evolution of a bulk scalar field in anti-de Sitter (AdS) spacetime linearly coupled to a scalar field on a de Sitter boundary brane. We present results of a spectral analysis of the system, and find that the model can exhibit both bound and continuum resonant modes. We find that zero, one, or two bound states may exist, depending upon the masses of the brane and bulk fields relative to the Hubble length and the AdS curvature scale and the coupling strength. In...

This is the first of two papers studying localization of massive bulk fields on a bane in 5D anti-de Sitter spacetime, and some of their cosmological consequences. Here we focus on a massive 5D scalar, which is known to lack a localized mode, and discuss how a seeming discontinuity between this theory and the massless theory - known to support a localized zero mode - is resolved thanks to peculiar analytic properties of the massive two-point amplitude. Furthermore, we propose...

We derive the scalar potential in zero mode effective action arising from a de Sitter brane embedded in five dimensions with bulk cosmological constant $\Lambda$. The scalar potential for a scalar field canonically normalized is given by the sum of exponential potentials. In the case of $\Lambda=0$ and $\Lambda>0$, we point out that the scalar potential has an unstable local maximum at the origin and exponentially vanishes for large positive scalar field. In the case of $\Lam...

We study two issues, the localization of various spin fields, and the problem of the cosmological constant on a brane in five-dimensional anti de Sitter space. We find that spin-zero fields are localized on a positive-tension brane. In addition to the localized zero-mode there is a continuous tower of states with no mass gap. Spin one-half and three-half states can be localized on a brane with ``negative tension''. Their localization can be achieved on the positive-tension br...