[1] Modern physics deals with three basic types of spatial symmetry: reflection, rotation, and translation.
Parity violation in weak interactions was first postulated by Tsung Dao Lee and Chen Ning Yang[2] in 1956 as a solution to the τ-θ puzzle.
In consultation with the experimental physicist Chien-Shiung Wu a number of possibilities were proposed to test whether the weak interaction was in fact invariant under parity.
Wu performed this experiment at the National Bureau of Standards in Washington, D.C. after nine months of work.
Contrary to most expectations, in December 1956 she and her team observed anisotropic electron radiation, proving that the weak interactions of the known particles violate parity.
Mirror particles have therefore been suggested as candidates for the inferred dark matter in the universe.
[14][15][16][17][18] In another context,[19] mirror matter has been proposed to give rise to an effective Higgs mechanism responsible for the electroweak symmetry breaking.
Sheldon Glashow has shown that if at some high energy scale particles exist which interact strongly with both ordinary and mirror particles, radiative corrections will lead to a mixing between photons and mirror photons.
In the latter case, the quantum corrections have to vanish at the one and two loop-level Feynman diagrams, otherwise the predicted value of the kinetic mixing parameter would be larger than experimentally allowed.
[24][25] Mirror matter may also be detected in electromagnetic field penetration experiments[26] and there would also be consequences for planetary science[27][28] and astrophysics.
[31][32][33][34] If mirror matter is present in the universe with sufficient abundance then its gravitational effects can be detected.
[42] Current research looks for signals where an applied magnetic field adjust the energy level of the neutron to the mirror world.
[46] Experiments searching for mirror neutron oscillation are ongoing at the Paul Scherrer Institute's UCN source[45] in Switzerland, Institut Laue-Langevin in France, and via the Spallation Neutron Source at the Oak Ridge National Laboratory in the U.S.[44][47]