2017-03-17 04:59:31 +00:00
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/*************************************************************************************
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Grid physics library, www.github.com/paboyle/Grid
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Source file: ./lib/qcd/modules/topological_charge.h
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Copyright (C) 2017
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Author: Guido Cossu <guido.cossu@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
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directory
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*************************************************************************************/
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/* END LEGAL */
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#ifndef HMC_TOP_CHARGE_H
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#define HMC_TOP_CHARGE_H
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namespace Grid {
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namespace QCD {
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2017-03-17 04:59:31 +00:00
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// this is only defined for a gauge theory
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template <class Impl>
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class TopologicalCharge : public HmcObservable<typename Impl::Field> {
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public:
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2017-03-17 07:14:57 +00:00
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// here forces the Impl to be of gauge fields
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// if not the compiler will complain
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INHERIT_GIMPL_TYPES(Impl);
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2017-03-17 04:59:31 +00:00
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2017-03-17 07:14:57 +00:00
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// necessary for HmcObservable compatibility
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typedef typename Impl::Field Field;
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void TrajectoryComplete(int traj,
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Field &U,
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GridSerialRNG &sRNG,
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GridParallelRNG &pRNG) {
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// 4d topological charge
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// Bx = -iF(y,z), By = -iF(z,y), Bz = -iF(x,y)
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GaugeLinkField Bx(U._grid), By(U._grid), Bz(U._grid);
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WilsonLoops<Impl>::FieldStrength(Bx, U, Ydir, Zdir);
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WilsonLoops<Impl>::FieldStrength(By, U, Zdir, Xdir);
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WilsonLoops<Impl>::FieldStrength(Bz, U, Xdir, Ydir);
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// Ex = -iF(t,x), Ey = -iF(t,y), Ez = -iF(t,z)
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GaugeLinkField Ex(U._grid), Ey(U._grid), Ez(U._grid);
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WilsonLoops<Impl>::FieldStrength(Ex, U, Tdir, Xdir);
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WilsonLoops<Impl>::FieldStrength(Ey, U, Tdir, Ydir);
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WilsonLoops<Impl>::FieldStrength(Ez, U, Tdir, Zdir);
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double coeff = 8.0/(32.0*M_PI*M_PI);
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2017-03-17 07:14:57 +00:00
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LatticeComplex qfield = coeff*trace(Bx*Ex + By*Ey + Bz*Ez);
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TComplex Tq = sum(qfield);
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Real q = TensorRemove(Tq).real();
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int def_prec = std::cout.precision();
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std::cout << GridLogMessage
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<< std::setprecision(std::numeric_limits<Real>::digits10 + 1)
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<< "Topological Charge: [ " << traj << " ] "<< q << std::endl;
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std::cout.precision(def_prec);
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}
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};
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}
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2017-03-17 04:59:31 +00:00
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}
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#endif // HMC_TOP_CHARGE_H
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