| da0e9ce3 |
1 | //-------------------------------------------------------------------------- |
| 2 | // |
| 3 | // Environment: |
| 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. |
| 7 | // |
| 8 | // Copyright Information: See EvtGen/COPYRIGHT |
| 9 | // Copyright (C) 1998 Caltech, UCSB |
| 10 | // |
| 11 | // Module: EvtEtaDalitz.cc |
| 12 | // |
| 13 | // Description: Routine to decay eta -> pi+ pi- pi0 |
| 14 | // |
| 15 | // Modification history: |
| 16 | // |
| 17 | // DJL/RYD July 23, 1997 Module created |
| 18 | // |
| 19 | //------------------------------------------------------------------------ |
| 20 | // |
| 21 | #include "EvtGenBase/EvtPatches.hh" |
| 22 | #include <stdlib.h> |
| 23 | #include "EvtGenBase/EvtParticle.hh" |
| 24 | #include "EvtGenBase/EvtGenKine.hh" |
| 25 | #include "EvtGenBase/EvtPDL.hh" |
| 26 | #include "EvtGenModels/EvtEtaDalitz.hh" |
| 27 | #include "EvtGenBase/EvtReport.hh" |
| 28 | #include <string> |
| 29 | |
| 30 | EvtEtaDalitz::~EvtEtaDalitz() {} |
| 31 | |
| 32 | std::string EvtEtaDalitz::getName(){ |
| 33 | |
| 34 | return "ETA_DALITZ"; |
| 35 | |
| 36 | } |
| 37 | |
| 38 | |
| 39 | EvtDecayBase* EvtEtaDalitz::clone(){ |
| 40 | |
| 41 | return new EvtEtaDalitz; |
| 42 | |
| 43 | } |
| 44 | |
| 45 | void EvtEtaDalitz::init(){ |
| 46 | |
| 47 | // check that there are 0 arguments |
| 48 | checkNArg(0); |
| 49 | checkNDaug(3); |
| 50 | |
| 51 | checkSpinParent(EvtSpinType::SCALAR); |
| 52 | |
| 53 | checkSpinDaughter(0,EvtSpinType::SCALAR); |
| 54 | checkSpinDaughter(1,EvtSpinType::SCALAR); |
| 55 | checkSpinDaughter(2,EvtSpinType::SCALAR); |
| 56 | } |
| 57 | |
| 58 | |
| 59 | void EvtEtaDalitz::initProbMax(){ |
| 60 | |
| 61 | setProbMax(2.1); |
| 62 | |
| 63 | } |
| 64 | |
| 65 | void EvtEtaDalitz::decay( EvtParticle *p){ |
| 66 | |
| 67 | p->initializePhaseSpace(getNDaug(),getDaugs()); |
| 68 | |
| 69 | EvtVector4R mompi0 = p->getDaug(2)->getP4(); |
| 70 | double masspip = p->getDaug(0)->mass(); |
| 71 | double masspim = p->getDaug(1)->mass(); |
| 72 | double masspi0 = p->getDaug(2)->mass(); |
| 73 | double m_eta = p->mass(); |
| 74 | |
| 75 | double y; |
| 76 | |
| 77 | //The decay amplitude coems from Layter et al PRD 7 2565 (1973). |
| 78 | |
| 79 | y=(mompi0.get(0)-masspi0)*(3.0/(m_eta-masspip-masspim-masspi0))-1.0; |
| 80 | |
| 81 | EvtComplex amp(sqrt(1.0-1.07*y),0.0); |
| 82 | |
| 83 | vertex(amp); |
| 84 | |
| 85 | return ; |
| 86 | |
| 87 | } |
| 88 | |
| 89 | |
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