mescomp_w.cc

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//  $Id: mescomp_w.cc,v 3.0 2006-04-03 04:59:00 edwards Exp $
/*! \file
 *  \brief Construct all components of a meson propagator
 */
 
#include "chromabase.h"
#include "meas/hadron/mescomp_w.h"
 
namespace Chroma 
{
 
  //! Convert generalized correlator object
  void convertMescomp(multi1d<Complex>& mesprop_1d, const multiNd<Complex>& mesprop, 
                      const int j_decay)
  {
    int length = Layout::lattSize()[j_decay]; // Temporal extent of lattice
 
    multi1d<int> ranks(5);
 
    mesprop_1d.resize(length*Ns*Ns*Ns*Ns);
 
    int cnt = 0;
    for(ranks[0]=0; ranks[0] < Ns; ++ranks[0])           // sf_2
      for(ranks[1]=0; ranks[1] < Ns; ++ranks[1])         // sf_1
        for(ranks[2]=0; ranks[2] < Ns; ++ranks[2])       // si_2
          for(ranks[3]=0; ranks[3] < Ns; ++ranks[3])     // si_1
            for(ranks[4] = 0; ranks[4] < length; ++ranks[4])
            {
              mesprop_1d[cnt++] = mesprop[ranks];
            }
  }
 
 
  //! Construct all components of a meson propagator
  /*!
   * \ingroup hadron
   *
   * This routine is specific to Wilson fermions!
   *
   * In all mesons the colour components are contracted leaving only the
   * spin components.
   *
   * \param mesprop                  meson correlation function (in real space) ( Write )
   * \param quark_propagator_1       quark propagator ( Read )
   * \param quark_propagator_2       quark propagator ( Read )
   * \param phases                   object holds list of momenta ( Read )
   * \param t0                       coordinates of source in decay direction ( Read )
   */
 
  void mescomp(multiNd<Complex>& mesprop,
               const LatticePropagator& quark_propagator_1, 
               const LatticePropagator& quark_propagator_2,
               const SftMom& phases,
               int t0)
  {
    START_CODE();
 
    // Length of lattice in decay direction
    int length  = phases.numSubsets();
    int j_decay = phases.getDir();
    int G5      = Ns*Ns-1;
 
    multi1d<DComplex> hsum;
  
    multi1d<int> ranks(5);
    ranks = Ns;
    ranks[4] = length;
    mesprop.resize(ranks);
 
    LatticePropagator antiquark_1 = adj(Gamma(G5) * quark_propagator_1 * Gamma(G5));
    LatticeComplex m_prop;
 
    for(ranks[0]=0; ranks[0] < Ns; ++ranks[0])           // sf_2
      for(ranks[1]=0; ranks[1] < Ns; ++ranks[1])         // sf_1
        for(ranks[2]=0; ranks[2] < Ns; ++ranks[2])       // si_2
          for(ranks[3]=0; ranks[3] < Ns; ++ranks[3])     // si_1
          {
            // Contract over color indices with antisym tensors
            m_prop = 
              traceColor(peekSpin(antiquark_1,
                                  ranks[1],ranks[3])   // (sf_1,si_1)
                       * peekSpin(quark_propagator_2,
                                  ranks[0],ranks[2])); // (sf_2,si_2)
 
            /* Project on zero momentum: Do a slice-wise sum. */
            hsum = sumMulti(m_prop, phases.getSet());
      
            for(ranks[4] = 0; ranks[4] < length; ++ranks[4])   // t
            {
              int t_eff = (ranks[4] - t0 + length) % length;
              mesprop[ranks] = hsum[t_eff];
            }
          }
 
    END_CODE();
  }
 
}  // end namespace Chroma