FIELD LOCALIZATION IN FIVE-DIMENSIONAL BRANEWORLD MODELS

• Main Author: WULANDARI (NIM : 30213007), DEWI
• Format: Dissertations
• Language: Indonesia
• Subjects: Fisika
• Online Access: https://digilib.itb.ac.id/gdl/view/26564
• Institution: Institut Teknologi Bandung

This dissertation discusses localization properties of fundamental fields or matter fields both in the modified Randall-Sundrum (MRS) and in the original Randall-Sundrum (RS) five-dimensional braneworld models. The localization properties correspond to the fact that matter fields live in a four-dimensional spacetime. The metrics of these models represent two different spacetimes as shown, among others, by different expressions of the Ricci scalar. The following cases were studied: i) minimal coupling of matter fields with gravity; ii) non-minimal coupling of matter fields with gravity; iii) interacting matter fields through a gauge mechanism. The localization properties are related to the finiteness of integrals over extra coordinates in the action. In analyzing the localization properties one should derive the field equation and obtain the extra coordinate part solution of the matter field that fulfils localization conditions. The solution of fields which satisfy the localization conditions describes the dynamics of the fields on a (3+1)- dimensional brane imbedded in a higher dimensional spacetime. In fact the two brane-world models under study have different localization properties of fields. The localization properties of matter fields coupled minimally to gravity in the MRS model are the following: i) massless vector fields are localizable on the brane only for decreasing warp factor while massive and massless scalar fields are localizable both for decreasing and increasing warp factors; ii) massive spinor fields are localizable on the brane for an increasing warp factor. In the RS model, on the other hand, matter fields coupled minimally to gravity has the following properties: i) massless and massive scalar fields are localizable on the brane for a decreasing warp factor; ii) massless vector fields are not localizable on the brane for both types of warp parameters; iii) spinor fields are localizable on the brane for an increasing warp factor. For the case of matter fields coupled non-minimally to gravity we have the following results in the MRS model: i) massive and massless scalar fields are not localizable on the brane; ii) massless and massive vector fields are not localizable on the brane; iii) massless spinor fields are localizable for an increasing warp factor only. Meanwhile, in the RS model we have the following results: i) massless and massive scalar fields are not localizable on the brane; ii) massless and massive vector fields are not localizable on the brane; iii) massless spinor fields are localizable for an increasing warp factor. In regards to the localization properties of fundamental fields which are coupled to one another through the gauge mechanism (interacting fields) i.e. for the case of scalar-vector, spinor-vector and vector-vector configurations under the background of MRS and RS metrics, we obtain the following: all configurations are not localizable on the brane in the RS model while they are localizable on the brane in the MRS model, even though only for a decreasing warp factor. The fact that the MRS and RS models provide localizability of fields with different types of warp factor shows that these two models still have not been yet as ideal models. An ideal braneworld model can localize all fields with one specific type of warp factor i.e. decreasing or increasing.