1 //--------------------------------------------------------------------------
4 // This software is part of the EvtGen package developed jointly
5 // for the BaBar and CLEO collaborations. If you use all or part
6 // of it, please give an appropriate acknowledgement.
8 // Copyright Information: See EvtGen/COPYRIGHT
9 // Copyright (C) 1998 Caltech, UCSB
11 // Module: EvtResonance2.cc
13 // Description: resonance-defining class
15 // Modification history:
17 // NK September 4, 1997 Module created
19 //------------------------------------------------------------------------
21 #include "EvtGenBase/EvtPatches.hh"
23 #include "EvtGenBase/EvtVector4R.hh"
24 #include "EvtGenBase/EvtKine.hh"
25 #include "EvtGenBase/EvtComplex.hh"
26 #include "EvtGenBase/EvtResonance2.hh"
27 #include "EvtGenBase/EvtReport.hh"
28 #include "EvtGenBase/EvtConst.hh"
30 EvtResonance2::~EvtResonance2(){}
32 EvtResonance2& EvtResonance2::operator = ( const EvtResonance2 &n)
34 if ( &n == this ) return *this;
43 _invmass_angdenom = n._invmass_angdenom;
48 EvtResonance2::EvtResonance2(const EvtVector4R& p4_p, const EvtVector4R& p4_d1,
49 const EvtVector4R& p4_d2, double ampl,
50 double theta, double gamma, double bwm, int spin,
51 bool invmass_angdenom):
52 _p4_p(p4_p),_p4_d1(p4_d1), _p4_d2(p4_d2),_ampl(ampl), _theta(theta),
53 _gamma(gamma), _bwm(bwm), _spin(spin), _invmass_angdenom(invmass_angdenom) {}
56 EvtComplex EvtResonance2::resAmpl() {
58 double pi180inv = 1.0/EvtConst::radToDegrees;
61 EvtVector4R p4_d3 = _p4_p-_p4_d1-_p4_d2;
63 //get cos of the angle between the daughters from their 4-momenta
64 //and the 4-momentum of the parent
66 //in general, EvtDecayAngle(parent, part1+part2, part1) gives the angle
67 //the missing particle (not listed in the arguments) makes
68 //with part2 in the rest frame of both
69 //listed particles (12)
71 //angle 3 makes with 2 in rest frame of 12 (CS3)
72 //double cos_phi_0 = EvtDecayAngle(_p4_p, _p4_d1+_p4_d2, _p4_d1);
73 //angle 3 makes with 1 in 12 is, of course, -cos_phi_0
75 //first compute several quantities...follow CLEO preprint 00-23
77 double mAB=(_p4_d1+_p4_d2).mass();
78 double mBC=(_p4_d2+p4_d3).mass();
79 double mAC=(_p4_d1+p4_d3).mass();
80 double mA=_p4_d1.mass();
81 double mB=_p4_d2.mass();
82 double mD=_p4_p.mass();
83 double mC=p4_d3.mass();
87 double mdenom = _invmass_angdenom ? mAB : mR;
88 double pAB=sqrt( (((mAB*mAB-mA*mA-mB*mB)*(mAB*mAB-mA*mA-mB*mB)/4.0) -
89 mA*mA*mB*mB)/(mAB*mAB));
90 double pR=sqrt( (((mR*mR-mA*mA-mB*mB)*(mR*mR-mA*mA-mB*mB)/4.0) -
91 mA*mA*mB*mB)/(mR*mR));
93 double pD= (((mD*mD-mR*mR-mC*mC)*(mD*mD-mR*mR-mC*mC)/4.0) -
95 if ( pD>0 ) { pD=sqrt(pD); } else {pD=0;}
96 double pDAB=sqrt( (((mD*mD-mAB*mAB-mC*mC)*(mD*mD-mAB*mAB-mC*mC)/4.0) -
97 mAB*mAB*mC*mC)/(mD*mD));
111 fR=sqrt(1.0+1.5*1.5*pR*pR)/sqrt(1.0+1.5*1.5*pAB*pAB);
112 fD=sqrt(1.0+5.0*5.0*pD*pD)/sqrt(1.0+5.0*5.0*pDAB*pDAB);
116 fR = sqrt( (9+3*pow((1.5*pR),2)+pow((1.5*pR),4))/(9+3*pow((1.5*pAB),2)+pow((1.5*pAB),4)) );
117 fD = sqrt( (9+3*pow((5.0*pD),2)+pow((5.0*pD),4))/(9+3*pow((5.0*pDAB),2)+pow((5.0*pDAB),4)) );
121 report(INFO,"EvtGen") << "Incorrect spin in EvtResonance22.cc\n";
124 double gammaAB= gammaR*pow(pAB/pR,power)*(mR/mAB)*fR*fR;
127 ampl=_ampl*EvtComplex(cos(_theta*pi180inv),sin(_theta*pi180inv))*
128 fR*fD/(mR*mR-mAB*mAB-EvtComplex(0.0,mR*gammaAB));
131 ampl=_ampl*EvtComplex(cos(_theta*pi180inv),sin(_theta*pi180inv))*
132 (fR*fD*(mAC*mAC-mBC*mBC+((mD*mD-mC*mC)*(mB*mB-mA*mA)/(mdenom*mdenom)))/
133 (mR*mR-mAB*mAB-EvtComplex(0.0,mR*gammaAB)));
136 ampl=_ampl*EvtComplex(cos(_theta*pi180inv),sin(_theta*pi180inv))*
137 fR*fD/(mR*mR-mAB*mAB-EvtComplex(0.0,mR*gammaAB))*
138 (pow((mBC*mBC-mAC*mAC+(mD*mD-mC*mC)*(mA*mA-mB*mB)/(mdenom*mdenom)),2)-
139 (1.0/3.0)*(mAB*mAB-2*mD*mD-2*mC*mC+pow((mD*mD- mC*mC)/mdenom, 2))*
140 (mAB*mAB-2*mA*mA-2*mB*mB+pow((mA*mA-mB*mB)/mdenom,2)));
144 report(INFO,"EvtGen") << "Incorrect spin in EvtResonance22.cc\n";