goldstinogravitino

Goldstinogravitino is a hypothetical fermionic state discussed in some supersymmetry (SUSY) breaking frameworks. The term refers to an effective degree of freedom that mixes, or behaves as a bound state of, the Goldstino and the gravitino—two fermionic modes that arise when SUSY is broken and generalized spacetime symmetries are gauged. In global SUSY, spontaneous breaking yields a massless Goldstino; in supergravity, the Goldstino is absorbed to form the gravitino through the super-Higgs mechanism. In certain constructions, such as models with multiple SUSY-breaking sectors or strong dynamics, linear combinations of these fermions can persist at low energies as mixed states or pseudo-Goldstini. The goldstinogravitino is thus used to describe such a mixed or composite state that inherits couplings from both constituents.

Properties of the goldstinogravitino depend on the details of the underlying theory. It is typically envisioned as a spin-1/2 fermion with a mass influenced by the SUSY-breaking scales and the gravitino mass. Its interactions can include both gravitino-like couplings, suppressed by the Planck scale, and Goldstino-like couplings tied to the SUSY-breaking sector. Possible production channels include decays of heavier SUSY states and high-energy collisions, with decays potentially yielding Standard Model particles plus missing energy.

Phenomenologically, the existence of a goldstinogravitino would alter collider signatures and cosmological considerations in SUSY models, particularly those related to gravitino phenomenology and the SUSY-breaking scale. As of now, there is no experimental evidence for such a state, and it remains a theoretical construct used to explore the consequences of mixing between Goldstino and gravitino degrees of freedom.

See also: Goldstino, Gravitino, Supersymmetry breaking, Pseudo-Goldstino.