Scalar fields within warped extra dimension

In this thesis, we explored three different implications of scalar fields in warped extra-dimension. First, scalar fields were employed to dynamically generate singular branes in Randall-Sundrum (RS)-like models by appropriate profiles --- the smooth/thick-branes. In the context of thick-branes, we constructed four different setups: (i) a smooth generalization of RS2 where a scalar field dynamically generates a singular brane allowing symmetric or asymmetric warped geometries on either side of the brane; (ii) a double thick-brane scenario which mimics two positive tension branes and allows to address the hierarchy problem; (iii) a Z_2 symmetric triple thick-brane; and (iv) a dilatonic thick-brane scenario. The stability of background solution is verified in all the above mentioned setups. Second, we considered a thick-brane cosmological model with warped fifth-dimension where the dynamics of the 4D universe is driven by the time-dependent 5D background. Different scenarios were found for which the cosmic scale factor a(t,y) and the scalar field \phi(t,y) depend non-trivially on the time t and the 5th-dimension y. Third, we discussed a symmetric 5D model with three D3-branes (IR--UV--IR) where the Higgs doublet and the other Standard Model (SM) fields are embedded in the bulk. The Z_2 geometric symmetry led to the warped KK-parity for all the bulk fields. Within this setup we investigated the low-energy effective theory for the bulk SM bosonic sector. It turned out that the zero-mode scalar sector contains an even scalar which mimics the SM Higgs boson and a second, stable odd scalar particle which is a dark matter candidate. The model that resulted from the Z_2-symmetric background geometry resembles the Inert Two Higgs Doublet Model. Implications for dark matter were discussed within this model.