Gaugino Condensation
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In
quantum field theory In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct phy ...
, gaugino condensation is the nonzero
vacuum expectation value In quantum field theory, the vacuum expectation value (VEV) of an operator is its average or expectation value in the vacuum. The vacuum expectation value of an operator O is usually denoted by \langle O\rangle. One of the most widely used exa ...
in some models of a bilinear expression constructed in theories with
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 ...
from the
superpartner In particle physics, a superpartner (also sparticle) is a class of hypothetical elementary particles predicted by supersymmetry, which, among other applications, is one of the well-studied ways to extend the Standard Model of high-energy physics. ...
of a gauge boson called the gaugino. The gaugino and the bosonic gauge field and the D-term are all components of a supersymmetric vector superfield in the Wess–Zumino gauge. : \langle \lambda^a_\alpha \lambda^b_\beta\rangle \sim \delta^\epsilon_\Lambda^3 where \lambda represents the gaugino field (a
spinor In geometry and physics, spinors (pronounced "spinner" IPA ) are elements of a complex numbers, complex vector space that can be associated with Euclidean space. A spinor transforms linearly when the Euclidean space is subjected to a slight (infi ...
) and \Lambda is an energy scale, and represent Lie algebra indices and and represent van der Waerden (two component spinor) indices. The mechanism is somewhat analogous to
chiral symmetry breaking In particle physics, chiral symmetry breaking generally refers to the dynamical spontaneous breaking of a chiral symmetry associated with massless fermions. This is usually associated with a gauge theory such as quantum chromodynamics, the quant ...
and is an example of a
fermionic condensate A fermionic condensate (or Fermi–Dirac condensate) is a superfluid phase formed by fermionic particles at low temperatures. It is closely related to the Bose–Einstein condensate, a superfluid phase formed by bosonic atoms under similar con ...
. In the superfield notation, W_\alpha \equiv \overline^2 D_\alpha V is the gauge field strength and is a chiral superfield. : \langle W^a_\alpha W^b_\beta \rangle = \langle \lambda^a_\alpha \lambda^b_\beta\rangle \sim \delta^\epsilon_\Lambda^3 W_\alpha W_\beta is also a chiral superfield and we see that what acquires a nonzero VEV is not the F-term of this chiral superfield. Because of this, gaugino condensation in and of itself does not lead to supersymmetry breaking. If we also have supersymmetry breaking, it is caused by something other than the gaugino condensate. However, a gaugino condensate definitely breaks U(1)R symmetry as \lambda^a_\alpha \lambda^b_\beta has an R-charge of 2.


See also

*
Tachyon condensation Tachyon condensation is a process in particle physics in which a system can lower its potential energy by spontaneously producing particles. The end result is a "condensate" of particles that fills the volume of the system. Tachyon condensation is ...


References

Supersymmetric quantum field theory Gauge theories {{quantum-stub