axgauge.cc

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/*! \file
 *  \brief Axial gauge fixing 
 */
 
#include "chromabase.h"
#include "meas/gfix/axgauge.h"
 
namespace Chroma 
{
 
  //! Axial gauge fixing
  /*!
   * \ingroup gfix
   *
   * Transfroms a gauge configuration, in place, into axial
   *            gauge with special direction decay_dir.
   *
   * Note: The non-unity time-like gauge fields from the last time slice
   *       will be copied to all other time slices.
   *
   * \param ug         gauge field and its axial gauge transform (Modify)
   * \param v          gauge rotation matrix (Write)
   * \param decay_dir  time direction (Read) 
   */
 
 
  void axGauge(multi1d<LatticeColorMatrix>& ug, int decay_dir)
  {
    START_CODE();
 
   START_CODE();
 
  int lsizet = Layout::lattSize()[decay_dir];
 
  LatticeColorMatrix v = 1;
  LatticeInteger t_coord = Layout::latticeCoordinate(decay_dir);
 
  /* Transform the "time-like" links to unity, slice by slice except for the */
  /* last slice and thereby construct the gauge transformation V. */
  for(int t = 1; t < lsizet; ++t)
  {
    LatticeBoolean btmp = t_coord == t;
 
    LatticeColorMatrix tmp_1 = shift(ug[decay_dir], BACKWARD, decay_dir);
    copymask(v, btmp, tmp_1);
    LatticeColorMatrix tmp_2 = tmp_1 * ug[decay_dir];
    copymask(ug[decay_dir], btmp, tmp_2);
  }
 
  /* Now do the gauge transformation on the space-like links */
  for(int mu = 0; mu < Nd; ++mu)
  {
    if ( mu != decay_dir )
    {
      LatticeColorMatrix tmp_2 = ug[mu] * shift(adj(v), FORWARD, mu);
      ug[mu] = v * tmp_2;
    }
  }
 
  /* Finally "broadcast" the t-link from the last time slice to all others */
  for(int t = lsizet-2; t >= 0; --t)
  {
    LatticeBoolean btmp = t_coord == t;
    
    copymask(ug[decay_dir], btmp, LatticeColorMatrix(shift(ug[decay_dir], FORWARD, decay_dir)));
  }
 
 
    END_CODE();
  }
 
}  // end namespace Chroma