The goldstino is the
Nambu–Goldstone fermion
In particle physics, a fermion is a subatomic particle that follows Fermi–Dirac statistics. Fermions have a half-integer spin (spin 1/2, spin , Spin (physics)#Higher spins, spin , etc.) and obey the Pauli exclusion principle. These particles i ...
emerging in the
spontaneous breaking of
supersymmetry
Supersymmetry is a Theory, theoretical framework in physics that suggests the existence of a symmetry between Particle physics, particles with integer Spin (physics), spin (''bosons'') and particles with half-integer spin (''fermions''). It propo ...
. 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 symmetry of a physical system is a physical or mathematical feature of the system (observed or intrinsic) that is preserved or remains unchanged under some transformation.
A family of particular transformations may be ''continuous'' (such ...
, the goldstino is an ordinary particle (possibly the lightest supersymmetric particle, responsible for
dark matter
In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...
).
In theories where supersymmetry is a
local symmetry
The symmetry of a physical system is a physical or mathematical feature of the system (observed or intrinsic) that is preserved or remains unchanged under some transformation.
A family of particular transformations may be ''continuous'' (such ...
, the goldstino is absorbed by the
gravitino
In supergravity theories combining general relativity and supersymmetry, the gravitino () is the gauge fermion supersymmetric partner of the hypothesized graviton. It has been suggested as a candidate for dark matter.
If it exists, it is a f ...
, the
gauge field
In physics, a gauge theory is a type of field theory in which the Lagrangian, and hence the dynamics of the system itself, does not change under local transformations according to certain smooth families of operations (Lie groups). Formally, t ...
it couples to, becoming its longitudinal component, and giving it nonvanishing mass. This mechanism
is a close analog of the way the
Higgs field
The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the excited state, quantum excitation of the Higgs field,
one of the field (physics), fields in particl ...
gives nonzero mass to the
W and Z bosons
In particle physics, the W and Z bosons are vector bosons that are together known as the weak bosons or more generally as the intermediate vector bosons. These elementary particles mediate the weak interaction; the respective symbols are , , an ...
.
Vestigial bosonic superpartners of the goldstinos, called ''
sgoldstino
A sgoldstino is any of the spin-0 superpartners of the goldstino in relativistic quantum field theories with spontaneously broken supersymmetry. The term ''sgoldstino'' was first used in 1998.
In 2016, Petersson and Torre hypothesized that a s ...
s'', might also appear, but need not, as
supermultiplet
In theoretical physics, a supermultiplet is a representation of a supersymmetry algebra, possibly with extended supersymmetry.
Then a superfield is a field on superspace which is valued in such a representation. Naïvely, or when considering ...
s have been reduced to arrays.
In effect, SSB of supersymmetry, by definition, implies a
nonlinear realization In mathematical physics, nonlinear realization of a Lie group ''G'' possessing a Cartan subgroup ''H'' is a particular induced representation of ''G''. In fact, it is a representation of a Lie algebra \mathfrak g of ''G'' in a neighborhood of its ...
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
Supersymmetric quantum field theory
Hypothetical elementary particles
{{Particle-stub