Brane World Susy Breaking from String/M Theory

TL;DR

This paper analyzes how supersymmetry breaking on hidden branes affects visible sector fields in string/M-theory models, highlighting non-universal scalar masses and potential flavor violations due to brane interactions.

Contribution

It demonstrates that brane interactions generally prevent sequestering, leading to non-universal scalar masses and flavor issues, with implications for model building in string/M-theory.

Findings

Brane-brane contact interactions induce non-universal scalar masses.

Sequestering is generally broken by bulk supergravity exchanges.

Certain compactifications can avoid tachyonic instabilities.

Abstract

String and M-theory realizations of brane world supersymmetry breaking scenarios are considered in which visible sector Standard Model fields are confined on a brane, with hidden sector supersymmetry breaking isolated on a distant brane. In calculable examples with an internal manifold of any volume the Kahler potential generically contains brane--brane non-derivative contact interactions coupling the visible and hidden sectors and is not of the no-scale sequestered form. This leads to non-universal scalar masses and without additional assumptions about flavor symmetries may in general induce dangerous sflavor violation even though the Standard Model and supersymmetry branes are physically separated. Deviations from the sequestered form are dictated by bulk supersymmetry and can in most cases be understood as arising from exchange of bulk supergravity fields between branes or warping of the internal geometry. Unacceptable visible sector tree-level tachyons arise in many models but may be avoided in certain classes of compactifications. Anomaly mediated and gaugino mediated contributions to scalar masses are sub-dominant except in special circumstances such as a flat or AdS pure five--dimensional bulk geometry without bulk vector multiplets.