Multiple supersymmetry-breaking sectors. Origins, spectra and uses.

I will discuss the physics of multiple supersymmetry (SUSY) breaking sectors. I will first focus on how multiple SUSY-breaking sectors could arise, paying particular attention to the possibility of multiple sequestered sectors, some of which may independently break SUSY spontaneously, and also considering how multiple SUSY-breaking sectors could arise as a consequence of the 'stimulated SUSY-breaking' mechanism. I will go on to describe how the low-energy particle content, the 'Goldstini', of each sector depends on how SUSY is broken within that sector, appealing to the example of the ISS models of SUSY-breaking. The masses of these multiple Goldstini also depend sensitively on how the sector is sequestered from the visible, or MSSM, sector, either through conformal sequestering or geographical sequestering in the context of warped throats of extra-dimensional scenarios. I will finally describe how the presence of multiple SUSY-breaking sectors can remedy some cosmological problems with gravitino over-production and will demonstrate that the 'stimulated SUSY-breaking' mechanism may be useful in simplifying models of gauge-mediation.