Induced brane gravity: realizations and limitations

TL;DR

The paper develops a detailed analysis of gravity induced on a brane by quantum loops of brane fields, focusing on thick-brane and compact scenarios, higher-derivative corrections, and a UV-complete D-brane realization. A key result is the emergence of a new threshold scale $E_b=1/\\sqrt{w r_c}$ for thick branes, with gravity potentially deviating from four-dimensional behavior below this scale; $R^2$ terms introduce additional thresholds and can alter gravity in unexpected regimes. In a compact setting, the threshold lies in the submillimeter range, making the effects potentially observable, while a string/D-brane construction yields calculable thresholds and regime transitions, including gravity screening and nontrivial KK-mode behavior. Overall, the work highlights rich, UV-sensitive low-energy phenomenology in induced-bravity brane models and cautions against overreliance on naive derivative-expansion arguments without a UV completion.

Abstract

The induced 4d gravity on a brane world is analyzed. The case of a thick brane is considered and the unexpected appearance of a new threshold scale, much larger than the thickness scale is found. In cases of phenomenological interest, this new length scale turns out to be in the submillimeter range. The effect of $R^2$ corrections, both in the bulk and on the brane, is also studied. It is shown that they introduce new threshold scales and may induce drastic modifications to the leading behavior. A concrete string/D-brane realization of the induced gravity scenario is also presented.