Gravity localization and mass hierarchy in scalar-tensor branes

Understand

We consider a braneworld model in the scalar-tensor gravity.

• In order to solve the gauge hierarchy problem in this model, our world should be confined on the positive tension brane rather than on the negative one.
• This is crucial to reproduce a correct Friedmann-like equation on the brane.
• Interestingly, it is found that the spacing of mass spectrum in this scenario is very tiny, but the light gravitons cannot be observed individually in colliders because of their sufficiently weak interaction with matter fields on the visible brane.