Are there braneworld models that have complete localization properties?

Abstract

A braneworld model is a model of (1+3+N)-dimensional space-time, called the bulk, with N extra dimensions where standard model particles are assumed to be localized on a (1+3)-dimensional “surface”, the so-called brane, embedded in the bulk. Gravitational fields, on the other hand, may propagate in the full space, the bulk. Some of the models could explain the weakness of the gravitational force relative to the other fundamental forces of nature. Among various models, the Randall-Sundrum (RS) model, an N = 1 braneworld model, has attracted much attention. Unfortunately, the assumption that standard model particles are trapped on the RS brane is not fully fulfilled. Accordingly, one of us with other colleagues proposed a modified RS model. The new model is conformally flat space-time and has much better localization properties. However, it is still not a perfect braneworld model since matter fields in some configurations are not localizable. This paper will elaborate localization properties of the model and discussed possible further modification to have a perfect model in terms of localization properties.