Conformal (2+4)-Braneworld

It is considered the 6D brane model where matter is trapped on the surface of a (2+4)-hyperboloid, as is suggested by the geometrical structure behind the 4D conformal group. The effective dimension of the bulk space-time for matter fields is five, with the extra space-like and time-like domains. Using the embedding theory the presence of the familiar factorizable 5D brane metrics in the both domains is shown. These metrics with exponential warp factors are able to provide with the additional reduction of the effective space-time dimensions down to four. It is demonstrated that the extra (1+1)-space is not simply connected and there is a gap in the range of the extra coordinates. This can explain stability of the model in the domain with the time-like effective fifth dimension and the appearance of the cosmological constant due to the tachyon condensation. It is found that the model exhibits orbifold symmetry and thus is free from the fermion chirality problem.