Brane to brane gravity mediation of supersymmetry breaking

TL;DR

This paper explores how supersymmetry breaking can be mediated through 5D supergravity in brane-world models, calculating quantum corrections that influence scalar masses and potentially resolve tachyonic issues.

Contribution

It extends supergravity formulations to include brane-to-brane supersymmetry mediation, providing calculable quantum effects and insights into scalar mass generation.

Findings

Radion-mediated contributions can make scalar masses positive.

Brane effects can fix tachyonic sleptons in anomaly mediation.

Calculations are based on off-shell 5D supergravity with localized matter.

Abstract

We extend the results of Mirabelli and Peskin to supergravity. We study the compactification on S_1/Z_2 of Zucker's off-shell formulation of 5D supergravity and its coupling to matter at the fixed points. We clarify some issues related to the off-shell description of supersymmetry breaking a la Scherk-Schwarz (here employed only as a technical tool) discussing how to deal with singular gravitino wave functions. We then consider `visible' and `hidden' chiral superfields localized at the two different fixed points and communicating only through 5D supergravity. We compute the one-loop corrections that mix the two sectors and the radion superfield. Locality in 5D ensures the calculability of these effects, which transmit supersymmetry breaking from the hidden to the visible sector. In the minimal set-up visible-sector scalars get a universal squared mass m_0^2 < 0. In general (e.g. in presence of a sizable gravitational kinetic term localized on the hidden brane) the radion-mediated contribution to m_0^2 can be positive and dominant. Although we did not build a complete satisfactory model, brane-to-brane effects can cure the tachyonic sleptons predicted by anomaly mediation by adding a positive m_0^2 which is universal up to subleading flavour-breaking corrections.