Low energy effective theory on a regularized brane in 6D gauged chiral supergravity

Abstract

We derive the low energy effective theory on a brane in six-dimensional chiral supergravity.The conical 3-brane singularities are resolved by introducing cylindrical 4-branes ofco-dimension 1 whose interiors are capped by a regular spacetime. The effective theoryis described by the Brans–Dicke (BD) theory with the BD parameter given byωBD = 1/2. The BD field originates from a modulus which is associated with the scaling symmetry ofthe system. If the dilaton potentials on the branes preserve the scaling symmetry, the scalarfield has an exponential potential in the Einstein frame. We show that the time dependentsolutions driven by the modulus in the four-dimensional effective theory can be lifted up tothe six-dimensional exact solutions found in the literature. On the basis of theeffective theory, we discuss a possible way to stabilize the modulus to recoverstandard cosmology and also study the implication for the cosmological constantproblem.