Gravitino
The Gravitino is a hypothetical elementary particle . In models that add general relativity and supersymmetry to the standard model , the gravitino is the supersymmetric partner of the likewise hypothetical graviton .
The Gravitino is a fermion with spin 3/2, its mass is either in the range keV / c² or TeV / c²; for comparison: the mass of the proton is 0.94 GeV / c².
If gravitinos exist and are heavy (TeV / c²), they only played a role in the early universe, especially for baryogenesis . Otherwise (keV / c²) they can also play a role in today's universe.
Light gravitino
If the gravitino is the lightest supersymmetric elementary particle (LSP) and the R-parity is (nearly) preserved, which would imply that the LSP is (nearly) stable, many - or all - supersymmetric particles of appreciable width could be included in their standard model- Super partner and a Gravitino disintegrate . This opens up different possibilities:
- The decays into a gravitino could be detected in particle accelerators . In the case of short lifetimes of the super partners, this can happen through disintegration inside the detector . In the case of longer lifetimes, the idea is to stop Charginos outside of the detector in order to let them disintegrate there. In principle, the Gravitino can be generated directly in particle collisions , for which a monojet signal is often expected (an energy deposition in only one region of the detector and missing energy due to the undetected Gravitino). The probability for such a production decreases with increasing mass of the gravitino, from which lower particle-physical limits for the gravitino mass can be given.
- In most supersymmetric models, the lightest neutralino is a candidate for dark matter , since many decays end up in this particle; the Particle Data Group gave 2019 as the experimental lower limit for its mass 46 GeV / c². A sufficiently light Gravitino (keV / c²) could take on the role of the LSP and thus become a candidate for dark matter.
See also
- Super gravity (SUGRA)