Adaptive Aggregation-based Domain Decomposition Multigrid for Twisted   Mass Fermions
  The Adaptive Aggregation-based Domain Decomposition Multigrid method (arXiv:1303.1377) is extended for two degenerate flavors of twisted mass fermions. By fine-tuning the parameters we achieve a speed-up of the order of hundred times compared to the conjugate gradient algorithm for the physical value of the pion mass. A thorough analysis of the aggregation parameters is presented, which provides a novel insight into multigrid methods for lattice QCD independently of the fermion discretization. 
Constantia Alexandrou, Simone Bacchio, Jacob Finkenrath, Andreas   Frommer, Karsten Kahl and Matthias Rottmann
hep-lat