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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: EvtVVSPwave.cc | |
12 | // | |
13 | // Description: Routine to decay vector-> vector pi pi where the | |
14 | // decay is S-wave dominated. | |
15 | // | |
16 | // Modification history: | |
17 | // | |
18 | // Jim Hunt June 4, 2008 Module Created | |
19 | // | |
20 | //------------------------------------------------------------------------ | |
21 | // | |
22 | #include "EvtGenBase/EvtPatches.hh" | |
23 | #include <stdlib.h> | |
24 | #include "EvtGenBase/EvtParticle.hh" | |
25 | #include "EvtGenBase/EvtGenKine.hh" | |
26 | #include "EvtGenBase/EvtPDL.hh" | |
27 | #include "EvtGenBase/EvtVector4C.hh" | |
28 | #include "EvtGenBase/EvtTensor4C.hh" | |
29 | #include "EvtGenBase/EvtReport.hh" | |
30 | #include "EvtGenModels/EvtVVPIPI_WEIGHTED.hh" | |
31 | #include <string> | |
32 | using std::endl; | |
33 | ||
34 | EvtVVPIPI_WEIGHTED::~EvtVVPIPI_WEIGHTED() {} | |
35 | ||
36 | std::string EvtVVPIPI_WEIGHTED::getName(){ | |
37 | ||
38 | return "VVPIPI_WEIGHTED"; | |
39 | ||
40 | } | |
41 | ||
42 | ||
43 | EvtDecayBase* EvtVVPIPI_WEIGHTED::clone(){ | |
44 | ||
45 | return new EvtVVPIPI_WEIGHTED; | |
46 | ||
47 | } | |
48 | ||
49 | void EvtVVPIPI_WEIGHTED::init(){ | |
50 | ||
51 | static EvtId PIP=EvtPDL::getId("pi+"); | |
52 | static EvtId PIM=EvtPDL::getId("pi-"); | |
53 | static EvtId PI0=EvtPDL::getId("pi0"); | |
54 | ||
55 | // check that there are 0 arguments | |
56 | checkNArg(0); | |
57 | checkNDaug(3); | |
58 | ||
59 | checkSpinParent(EvtSpinType::VECTOR); | |
60 | checkSpinDaughter(0,EvtSpinType::VECTOR); | |
61 | ||
62 | ||
63 | ||
64 | if ((!(getDaug(1)==PIP&&getDaug(2)==PIM))&& | |
65 | (!(getDaug(1)==PI0&&getDaug(2)==PI0))) { | |
66 | report(ERROR,"EvtGen") << "EvtVVPIPI_WEIGHTED generator expected " | |
67 | << " pi+ and pi- (or pi0 and pi0) " | |
68 | << "as 2nd and 3rd daughter. "<<endl; | |
69 | report(ERROR,"EvtGen") << "Will terminate execution!"<<endl; | |
70 | ::abort(); | |
71 | } | |
72 | ||
73 | } | |
74 | ||
75 | void EvtVVPIPI_WEIGHTED::initProbMax() { | |
76 | //Hard coded... should not be hard to calculate... | |
77 | setProbMax(0.08* 1.13 ); | |
78 | } | |
79 | ||
80 | double reweight_event(double pipi_mass) | |
81 | { | |
82 | pipi_mass *= 1000.0; | |
83 | return sqrt( | |
84 | -3.6911336508223251 + | |
85 | 0.019119831948029617 * pipi_mass + | |
86 | -1.8962883732377376e-05 * pipi_mass * pipi_mass | |
87 | ); | |
88 | } | |
89 | ||
90 | void EvtVVPIPI_WEIGHTED::decay( EvtParticle *psi_prime){ | |
91 | ||
92 | psi_prime->initializePhaseSpace(getNDaug(),getDaugs()); | |
93 | ||
94 | EvtParticle *jpsi,*pi1,*pi2; | |
95 | ||
96 | jpsi=psi_prime->getDaug(0); | |
97 | pi1=psi_prime->getDaug(1); | |
98 | pi2=psi_prime->getDaug(2); | |
99 | ||
100 | // Put phase space results into the daughters. | |
101 | ||
102 | EvtVector4C ep0,ep1,ep2; | |
103 | ||
104 | ep0=psi_prime->eps(0); | |
105 | ep1=psi_prime->eps(1); | |
106 | ep2=psi_prime->eps(2); | |
107 | ||
108 | EvtVector4C e0,e1,e2; | |
109 | ||
110 | e0 = jpsi->epsParent(0); | |
111 | e1 = jpsi->epsParent(1); | |
112 | e2 = jpsi->epsParent(2); | |
113 | ||
114 | double mass2 = (pi1->getP4()+pi2->getP4()).mass2(); | |
115 | ||
116 | double fac = mass2-4*pi1->mass()*pi2->mass(); | |
117 | ||
118 | fac *= reweight_event(sqrt(mass2)); | |
119 | ||
120 | vertex(0,0,fac*(ep0*e0.conj())); | |
121 | vertex(0,1,fac*(ep0*e1.conj())); | |
122 | vertex(0,2,fac*(ep0*e2.conj())); | |
123 | ||
124 | vertex(1,0,fac*(ep1*e0.conj())); | |
125 | vertex(1,1,fac*(ep1*e1.conj())); | |
126 | vertex(1,2,fac*(ep1*e2.conj())); | |
127 | ||
128 | vertex(2,0,fac*(ep2*e0.conj())); | |
129 | vertex(2,1,fac*(ep2*e1.conj())); | |
130 | vertex(2,2,fac*(ep2*e2.conj())); | |
131 | ||
132 | return ; | |
133 | ||
134 | } | |
135 |