include/EvtGenBase/EvtKine.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 EVTKINE_HH
0022 #define EVTKINE_HH
0023
0024 class EvtVector4R;
0025 class EvtComplex;
0026
0027 double EvtDecayAngle( const EvtVector4R&, const EvtVector4R&, const EvtVector4R& );
0028
0029 double EvtDecayAngleChi( const EvtVector4R&, const EvtVector4R&,
0030                          const EvtVector4R&, const EvtVector4R&,
0031                          const EvtVector4R& );
0032
0033 //
0034 // This routine calculates the cosine of the angle between
0035 // the normal of the decay plane and the flight direction of particle q
0036 // in the parent frame.
0037 //
0038 double EvtDecayPlaneNormalAngle( const EvtVector4R& p, const EvtVector4R& q,
0039                                  const EvtVector4R& d1, const EvtVector4R& d2 );
0040
0041 // Added by AJB
0042 //
0043 // Calculate phi (between 0 and 2 pi) of the daughter given the 4-momentum of
0044 // the grandparent, parent, resonance and the daughter.  g, p, q and d need to
0045 // be in the same rest frame.  Note that for the first level of the tree there
0046 // is no grandparent and thus <0,0,0,1> should be passed in for g.  When there
0047 // is no parent the angles need to be calculated by simply by calculating polar
0048 // and azymuthal angles in the rest frame of the resonance (since this will
0049 // generally be the root particle and is generally at rest the polar and
0050 // azymuthal angels can simply be calculated.
0051 //
0052 double EvtDecayAnglePhi( const EvtVector4R& g, const EvtVector4R& p,
0053                          const EvtVector4R& q, const EvtVector4R& d );
0054
0055 // Wigner big-D function in Jackson convention
0056 //
0057 // XXX NOTE XXX
0058 //  - EvtDecayAngle returns the cos \theta and EvtdFunction requires theta
0059 //  - In EvtdFunction j m1 and m2 are really 2 * j, 2 * m1, 2*m2 to deal with
0060 //    spin 1/2 particles
0061 //
0062 EvtComplex wignerD( int j, int m1, int m2, double phi, double theta,
0063                     double gamma );
0064
0065 //
0066 // Function to calculate momentum of daughters in two body decay in mothers
0067 // rest frame.
0068 double twoBodyMomentum( const double M, const double m1, const double m2 );
0069
0070 #endif