The goldstino is the Nambu−Goldstone fermion emerging in the spontaneous breaking of supersymmetry. It is the close fermionic analog of the Nambu−Goldstone bosons controlling the spontaneous breakdown of ordinary bosonic symmetries.
As in the case of Goldstone bosons, it is massless, unless there is, in addition, a small explicit supersymmetry breakdown involved, on top of the basic spontaneous breakdown; in this case it develops a small mass, analogous to that of Pseudo-Goldstone bosons of chiral symmetry breaking.
In theories where supersymmetry is a global symmetry, the goldstino is an ordinary particle (possibly the lightest supersymmetric particle, responsible for dark matter).
In theories where supersymmetry is a local symmetry, the goldstino is absorbed by the gravitino, the gauge field it couples to, becoming its longitudinal component, and giving it nonvanishing mass. This mechanism is a close analog of the way the Higgs field gives nonzero mass to the W and Z bosons.
Vestigial bosonic superpartners of the goldstinos, called sgoldstinos, might also appear, but need not, as supermultiplets have been reduced to arrays.[1][2][3] In effect, SSB of supersymmetry, by definition, implies a nonlinear realization of the supersymmetry in the Nambu−Goldstone mode, in which the goldstino couples identically to all particles in these arrays, and is thus the superpartner of all of them, equally.
References
- ^ Volkov, D.V.; Akulov, V. (1973). "Is the neutrino a goldstone particle?". Physics Letters. B46 (1): 109–110. Bibcode:1973PhLB...46..109V. doi:10.1016/0370-2693(73)90490-5.
- ^ Salam, A.; et al. (1974). "On Goldstone Fermion". Physics Letters. B49 (5): 465–467. Bibcode:1974PhLB...49..465S. doi:10.1016/0370-2693(74)90637-6.
- ^ Uematsu, T.; Zachos, C. K. (1982). "Structure of phenomenological lagrangians for broken supersymmetry". Nuclear Physics B. 201 (2): 250. Bibcode:1982NuPhB.201..250U. doi:10.1016/0550-3213(82)90431-X.