Abstract
Light gravitinos, with mass in the eV to MeV range, are well motivated in particle physics, but their status as dark-matter candidates is muddled by early-Universe uncertainties. We investigate how upcoming data from colliders may clarify this picture. Light gravitinos are produced primarily in the decays of the next-to-lightest supersymmetric particle, resulting in spectacular signals, including di-photons, delayed and nonpointing photons, kinked charged tracks, and heavy metastable charged particles. We find that the Tevatron with $20\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ and the 7 TeV LHC with $1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ may both see evidence for hundreds of light-gravitino events. Remarkably, this collider data is also well suited to distinguish between currently viable light-gravitino scenarios, with striking implications for structure formation, inflation, and other early-Universe cosmology.
Highlights
Supersymmetry is one of the most promising ideas for new physics beyond the standard model
We consider light gravitinos, with mass in the eV to MeV range. Such gravitinos are highly motivated in particle physics, as they emerge in models with gauge-mediated supersymmetry breaking (GMSB), in which constraints on flavor violation are naturally satisfied [5,6,7,8,9,10]
Light gravitinos in the mass range eV to MeV appear in GMSB models that naturally avoid flavor violation
Summary
Supersymmetry is one of the most promising ideas for new physics beyond the standard model. When originally proposed in the 1980s, uncertainties in h and the total matter relic density allowed mG~ $ keV This led to a simple and attractive gravitino–dark-matter scenario, consistent with standard big bang cosmology, in which the Universe cooled from some high temperature, and keV gravitinos froze out and form all of the dark matter. The decay length of a bino NLSP decaying to a gravitino is [13] This implies that scenarios 1, 2, and 3 make distinct predictions for collider phenomenology, and the identification of the gravitino collider signatures realized in nature may have far-reaching implications for the early Universe. This requires that gravitinos can be produced in sufficient numbers and distinguished from standard model backgrounds.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
