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177 lines
6.9 KiB
C++
177 lines
6.9 KiB
C++
/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./lib/qcd/utils/BaryonUtils.h
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Copyright (C) 2019
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Author: Felix Erben <felix.erben@ed.ac.uk>
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Author: Michael Marshall <Michael.Marshall@ed.ac.uk>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along
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with this program; if not, write to the Free Software Foundation, Inc.,
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51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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See the full license in the file "LICENSE" in the top level distribution directory
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*************************************************************************************/
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/* END LEGAL */
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#pragma once
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//#include <Grid/Hadrons/Global.hpp>
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#include <Grid/Eigen/unsupported/CXX11/Tensor>
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NAMESPACE_BEGIN(Grid);
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#undef DELTA_F_EQ_2
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template <typename FImpl>
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class BaryonUtils
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{
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public:
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typedef typename FImpl::ComplexField ComplexField;
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typedef typename FImpl::FermionField FermionField;
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typedef typename FImpl::PropagatorField PropagatorField;
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typedef typename FImpl::SitePropagator pobj;
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typedef typename FImpl::SiteSpinor vobj;
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typedef typename vobj::scalar_object sobj;
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typedef typename vobj::scalar_type scalar_type;
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typedef typename vobj::vector_type vector_type;
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static void ContractBaryons(const PropagatorField &q1_src,
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const PropagatorField &q2_src,
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const PropagatorField &q3_src,
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const Gamma GammaA,
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const Gamma GammaB,
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const char quarks_snk[],
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const char quarks_src[],
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const int parity,
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ComplexField &baryon_corr);
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};
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template<class FImpl>
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void BaryonUtils<FImpl>::ContractBaryons(const PropagatorField &q1_src,
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const PropagatorField &q2_src,
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const PropagatorField &q3_src,
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const Gamma GammaA,
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const Gamma GammaB,
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const char quarks_snk[],
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const char quarks_src[],
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const int parity,
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ComplexField &baryon_corr)
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{
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assert(parity==1 || parity == -1 && "Parity must be +1 or -1");
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GridBase *grid = q1_src.Grid();
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Gamma g4(Gamma::Algebra::GammaT); //needed for parity P_\pm = 0.5*(1 \pm \gamma_4)
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std::vector<std::vector<int>> epsilon = {{0,1,2},{1,2,0},{2,0,1},{0,2,1},{2,1,0},{1,0,2}};
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std::vector<int> epsilon_sgn = {1,1,1,-1,-1,-1};
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std::vector<int> wick_contraction = {0,0,0,0,0,0};
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for (int ie=0; ie < 6 ; ie++)
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if (quarks_src[0] == quarks_snk[epsilon[ie][0]] && quarks_src[1] == quarks_snk[epsilon[ie][1]] && quarks_src[2] == quarks_snk[epsilon[ie][2]])
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wick_contraction[ie]=1;
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typedef typename ComplexField::vector_object vobj;
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LatticeView<vobj> vbaryon_corr{ baryon_corr };
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accelerator_for(ss, grid->oSites(), grid->Nsimd(), {
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LatticeView<pobj> v1(q1_src);
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LatticeView<pobj> v2(q2_src);
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LatticeView<pobj> v3(q3_src);
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auto D1 = v1[ss];
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auto D2 = v2[ss];
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auto D3 = v3[ss];
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auto gD1a = GammaA * GammaA * D1;
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auto gD1b = GammaA * g4 * GammaA * D1;
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auto pD1 = 0.5* (gD1a + (double)parity * gD1b);
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auto gD3 = GammaB * D3;
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vobj result{ 0 };
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for (int ie_src=0; ie_src < 6 ; ie_src++){
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int a_src = epsilon[ie_src][0]; //a
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int b_src = epsilon[ie_src][1]; //b
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int c_src = epsilon[ie_src][2]; //c
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for (int ie_snk=0; ie_snk < 6 ; ie_snk++){
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int a_snk = epsilon[ie_snk][0]; //a'
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int b_snk = epsilon[ie_snk][1]; //b'
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int c_snk = epsilon[ie_snk][2]; //c'
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//This is the \delta_{456}^{123} part
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if (wick_contraction[0]){
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auto D2g = D2 * GammaB;
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for (int alpha_snk=0; alpha_snk<Ns; alpha_snk++){
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for (int beta_src=0; beta_src<Ns; beta_src++){
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for (int gamma_src=0; gamma_src<Ns; gamma_src++){
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result()()() += epsilon_sgn[ie_src] * epsilon_sgn[ie_snk] * pD1()(gamma_src,gamma_src)(c_snk,c_src)*D2g()(alpha_snk,beta_src)(a_snk,a_src)*gD3()(alpha_snk,beta_src)(b_snk,b_src);
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}}}
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}
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//This is the \delta_{456}^{231} part
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if (wick_contraction[1]){
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auto pD1g = pD1 * GammaB;
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for (int alpha_snk=0; alpha_snk<Ns; alpha_snk++){
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for (int beta_src=0; beta_src<Ns; beta_src++){
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for (int gamma_src=0; gamma_src<Ns; gamma_src++){
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result()()() += epsilon_sgn[ie_src] * epsilon_sgn[ie_snk] * pD1g()(gamma_src,beta_src)(c_snk,a_src)*D2()(alpha_snk,beta_src)(a_snk,b_src)*gD3()(alpha_snk,gamma_src)(b_snk,c_src);
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}}}
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}
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//This is the \delta_{456}^{312} part
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if (wick_contraction[2]){
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auto gD3g = gD3 * GammaB;
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for (int alpha_snk=0; alpha_snk<Ns; alpha_snk++){
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for (int beta_src=0; beta_src<Ns; beta_src++){
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for (int gamma_src=0; gamma_src<Ns; gamma_src++){
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result()()() += epsilon_sgn[ie_src] * epsilon_sgn[ie_snk] * pD1()(gamma_src,beta_src)(c_snk,b_src)*D2()(alpha_snk,gamma_src)(a_snk,c_src)*gD3g()(alpha_snk,beta_src)(b_snk,a_src);
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}}}
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}
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//This is the \delta_{456}^{132} part
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if (wick_contraction[3]){
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auto gD3g = gD3 * GammaB;
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for (int alpha_snk=0; alpha_snk<Ns; alpha_snk++){
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for (int beta_src=0; beta_src<Ns; beta_src++){
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for (int gamma_src=0; gamma_src<Ns; gamma_src++){
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result()()() -= epsilon_sgn[ie_src] * epsilon_sgn[ie_snk] * pD1()(gamma_src,gamma_src)(c_snk,c_src)*D2()(alpha_snk,beta_src)(a_snk,b_src)*gD3g()(alpha_snk,beta_src)(b_snk,a_src);
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}}}
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}
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//This is the \delta_{456}^{321} part
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if (wick_contraction[4]){
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auto D2g = D2 * GammaB;
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for (int alpha_snk=0; alpha_snk<Ns; alpha_snk++){
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for (int beta_src=0; beta_src<Ns; beta_src++){
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for (int gamma_src=0; gamma_src<Ns; gamma_src++){
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result()()() -= epsilon_sgn[ie_src] * epsilon_sgn[ie_snk] * pD1()(gamma_src,beta_src)(c_snk,b_src)*D2g()(alpha_snk,beta_src)(a_snk,a_src)*gD3()(alpha_snk,gamma_src)(b_snk,c_src);
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}}}
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}
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//This is the \delta_{456}^{213} part
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if (wick_contraction[5]){
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auto pD1g = pD1 * GammaB;
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for (int alpha_snk=0; alpha_snk<Ns; alpha_snk++){
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for (int beta_src=0; beta_src<Ns; beta_src++){
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for (int gamma_src=0; gamma_src<Ns; gamma_src++){
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result()()() -= epsilon_sgn[ie_src] * epsilon_sgn[ie_snk] * pD1g()(gamma_src,beta_src)(c_snk,a_src)*D2()(alpha_snk,gamma_src)(a_snk,c_src)*gD3()(alpha_snk,beta_src)(b_snk,b_src);
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}}}
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}
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}
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}
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vbaryon_corr[ss] = result;
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} );//end loop over lattice sites
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}
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NAMESPACE_END(Grid);
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