HISQ
HISQ, or Highly Improved Staggered Quark, is a lattice fermion action used in lattice quantum chromodynamics to simulate quarks on a discretized space-time lattice. It is an advancement of staggered fermions designed to suppress taste-symmetry violations and reduce discretization errors, enabling more accurate simulations of light and charm quarks. The action was developed by the MILC collaboration and collaborators as part of the evolution from ASQTAD improvements, and has become a standard choice for high-precision QCD calculations.
Technical features include two levels of link smearing (Fat7) with reunitarization, followed by an additional smearing
Impact and applications: HISQ reduces discretization errors compared with earlier staggered actions and is particularly effective
Related topics include staggered fermions, taste-symmetry breaking, ASQTAD, and lattice QCD.