Minimally doubled fermions realize one degenerate pair of Dirac fermions on the lattice.
Similarities to staggered fermions exist, namely, spin and taste degrees of freedom become
intertwined, and a remnant, non-singlet chiral symmetry and ultralocality are maintained.
However, charge conjugation, isotropy and some space-time reflection symmetries are broken
by the cutoff.
For two variants, i.e., Karsten-Wilczek (KW) or Borici-Creutz (BC) fermions, a tasted charge
conjugation symmetry can be identified, and the respective representations of the spin-taste
algebra can be constructed explicitly. In the case of BC fermions, the tasted symmetry
indicates that amendments to the published counterterms are necessary.
The spin-taste representation on the quark level permits construction of local or extended
hadron interpolating operators for any spin-taste combination, albeit with contamination by
parity partners and taste-symmetry violation. The few available numerical results for KW
fermions are in line with expectations.