include/EvtGenBase/EvtResonance.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 EVTRESONANCE_HH
0022 #define EVTRESONANCE_HH
0023
0024 #include "EvtGenBase/EvtVector4R.hh"
0025
0026 class EvtComplex;
0027
0028 class EvtResonance final {
0029   public:
0030     EvtResonance& operator=( const EvtResonance& );
0031
0032     //constructor with all information about the resonance
0033     EvtResonance( const EvtVector4R& p4_p, const EvtVector4R& p4_d1,
0034                   const EvtVector4R& p4_d2, double ampl = 0.0, double theta = 0.0,
0035                   double gamma = 0.0, double bwm = 0.0, int spin = 0 );
0036
0037     //accessors
0038     //return 4-momenta of the particles involved
0039     inline const EvtVector4R& p4_p() { return _p4_p; }
0040     inline const EvtVector4R& p4_d1() { return _p4_d1; }
0041     inline const EvtVector4R& p4_d2() { return _p4_d2; }
0042
0043     //return amplitude
0044     inline double amplitude() { return _ampl; }
0045
0046     //return theta
0047     inline double theta() { return _theta; }
0048
0049     //return gamma
0050     inline double gamma() { return _gamma; }
0051
0052     //return bwm
0053     inline double bwm() { return _bwm; }
0054
0055     //return spin
0056     inline int spin() { return _spin; }
0057
0058     //calculate amplitude for this resonance
0059     EvtComplex resAmpl();
0060
0061     //calculate relativistic Breit-Wigner amplitude for P-decays of scalars
0062     EvtComplex relBrWig( int i );
0063
0064   private:
0065     EvtVector4R _p4_p, _p4_d1, _p4_d2;
0066     double _ampl, _theta, _gamma, _bwm;
0067     int _spin;
0068 };
0069
0070 #endif