include/EvtGenBase/EvtEvalHelAmp.hh

0001
0002 /***********************************************************************
0003 * Copyright 1998-2020 CERN for the benefit of the EvtGen authors       *
0004 *                                                                      *
0005 * This file is part of EvtGen.                                         *
0006 *                                                                      *
0007 * EvtGen is free software: you can redistribute it and/or modify       *
0008 * it under the terms of the GNU General Public License as published by *
0009 * the Free Software Foundation, either version 3 of the License, or    *
0010 * (at your option) any later version.                                  *
0011 *                                                                      *
0012 * EvtGen is distributed in the hope that it will be useful,            *
0013 * but WITHOUT ANY WARRANTY; without even the implied warranty of       *
0014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        *
0015 * GNU General Public License for more details.                         *
0016 *                                                                      *
0017 * You should have received a copy of the GNU General Public License    *
0018 * along with EvtGen.  If not, see <https://www.gnu.org/licenses/>.     *
0019 ***********************************************************************/
0020
0021 #ifndef EVTEVALHELAMP_HH
0022 #define EVTEVALHELAMP_HH
0023
0024 #include "EvtGenBase/EvtDecayAmp.hh"
0025 #include "EvtGenBase/EvtId.hh"
0026 #include "EvtGenBase/EvtSpinType.hh"
0027
0028 class EvtParticle;
0029 class EvtAmp;
0030
0031 class EvtEvalHelAmp {
0032   public:
0033     EvtEvalHelAmp( EvtId idA, EvtId idB, EvtId idC, EvtComplexPtrPtr HBC );
0034
0035     virtual ~EvtEvalHelAmp();
0036
0037     double probMax();
0038
0039     void evalAmp( EvtParticle* p, EvtAmp& amp );
0040
0041   private:
0042     void fillHelicity( int* lambda2, int n, int J2, EvtId id );
0043     void setUpRotationMatrices( EvtParticle* p, double theta, double phi );
0044     void applyRotationMatrices();
0045
0046     //spins states available for particle A, B, and C.
0047     int _nA, _nB, _nC;
0048
0049     //helicity amplitudes
0050     EvtComplexPtrPtr _HBC;
0051
0052     //2 times spin for each of the particles
0053     int _JA2, _JB2, _JC2;
0054
0055     //2 times the helicity for the states
0056     int *_lambdaA2, *_lambdaB2, *_lambdaC2;
0057
0058     //Rotation matrices
0059     EvtComplexPtrPtr _RA, _RB, _RC;
0060
0061     //temporary array for amplitudes
0062     EvtComplexPtrPtrPtr _amp, _amp1, _amp3;
0063 };
0064
0065 #endif