Fix bug in building local list of valid files.
[u/mrichter/AliRoot.git] / TEvtGen / EvtGenModels / EvtY3SToY1SpipiMoxhay.cpp
CommitLineData
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: EvtGen/EvtVVpipiMoxhay.hh
12//
13// Description: This model is based on the proposal by Tuan and Lipkin
14// (Phys.Lett.B206:349-353,1988) and the subsequent model
15// by Moxhay (Phys.Rev.D39:3497,1989) for the dipion spectrum
16// in Y(3S) -> pi+ pi- Y(1S). Please Note: in Moxhay's paper,
17// he wrote the fitted value of the parameter Im(B)/A as
18// -0.2983. However, using his quoted value leads to the wrong
19// spectrum. Changing the sign of his quoted Im(B)/A fixes the
20// shape and reproduces his result. Therefore, please pass
21// Im(B)/A = 0.2983 and Re(B)/A = 0.2196 to get the correct shape
22// based on his fit to the CLEO data.
23//
24// Example:
25//
26// Decay Upsilon(3S)
27// 1.0000 Upsilon pi+ pi- Y3STOY1SPIPIMOXHAY 0.2196 0.2983;
28// Enddecay
29//
30// --> the order of parameters is: Re(B)/A Im(B)/A
31//
32// Modification history:
33//
34// SEKULA November 02, 2007 Module created
35//
36//------------------------------------------------------------------------
37
38
39#include "EvtGenBase/EvtPatches.hh"
40#include <stdlib.h>
41#include "EvtGenBase/EvtParticle.hh"
42#include "EvtGenBase/EvtGenKine.hh"
43#include "EvtGenBase/EvtPDL.hh"
44#include "EvtGenBase/EvtVector4C.hh"
45#include "EvtGenBase/EvtTensor4C.hh"
46#include "EvtGenBase/EvtReport.hh"
47#include "EvtGenModels/EvtY3SToY1SpipiMoxhay.hh"
48#include <string>
49using std::endl;
50
51EvtY3SToY1SpipiMoxhay::~EvtY3SToY1SpipiMoxhay() {}
52
53std::string EvtY3SToY1SpipiMoxhay::getName(){
54
55 return "Y3STOY1SPIPIMOXHAY";
56
57}
58
59
60EvtDecayBase* EvtY3SToY1SpipiMoxhay::clone(){
61
62 return new EvtY3SToY1SpipiMoxhay;
63
64}
65
66void EvtY3SToY1SpipiMoxhay::init(){
67
68 static EvtId PIP=EvtPDL::getId("pi+");
69 static EvtId PIM=EvtPDL::getId("pi-");
70 static EvtId PI0=EvtPDL::getId("pi0");
71
72 // check that there are 2 arguments
73 checkNArg(2);
74 checkNDaug(3);
75
76 checkSpinParent(EvtSpinType::VECTOR);
77 checkSpinDaughter(0,EvtSpinType::VECTOR);
78
79
80
81 if ((!(getDaug(1)==PIP&&getDaug(2)==PIM))&&
82 (!(getDaug(1)==PI0&&getDaug(2)==PI0))) {
83 report(ERROR,"EvtGen") << "EvtY3SToY1SpipiMoxhay generator expected "
84 << " pi+ and pi- (or pi0 and pi0) "
85 << "as 2nd and 3rd daughter. "<<endl;
86 report(ERROR,"EvtGen") << "Will terminate execution!"<<endl;
87 ::abort();
88 }
89
90}
91
92void EvtY3SToY1SpipiMoxhay::initProbMax() {
93 setProbMax(0.2);
94}
95
96void EvtY3SToY1SpipiMoxhay::decay( EvtParticle *p){
97
98 p->initializePhaseSpace(getNDaug(),getDaugs());
99
100 EvtParticle *v,*s1,*s2;
101
102 v=p->getDaug(0);
103 s1=p->getDaug(1);
104 s2=p->getDaug(2);
105
106
107 // setup the parameters needed for this model
108 double g_spp = 0.64;
109 double lambda = -0.73;
110 double m_sigma = 0.71;
111 double f_pi = 0.094;
112 double m_pi = s1->getP4().mass();
113
114 double MV1 = p->getP4().mass();
115 double MV2 = v->getP4().mass();
116
117 double q = (s1->getP4()+s2->getP4()).mass();
118
119 double EV2 = (MV1*MV1 - MV2*MV2 - q*q)/(2.0 * q);
120
121 double ReB_over_A = getArg(0);
122 double ImB_over_A = getArg(1);
123
124
125 EvtComplex Xi;
126
127 Xi = EvtComplex( 2.0/EvtConst::pi * ( 1.0 - sqrt(1.0 - 4*m_pi*m_pi/(q*q)) * log( (sqrt(q*q) + sqrt(q*q-4.0*m_pi*m_pi))/(2*m_pi) )),
128 sqrt(1.0 - 4*m_pi*m_pi/(q*q)));
129
130 // The form factor
131 EvtComplex F;
132
133 F = (g_spp*g_spp + lambda*(m_sigma*m_sigma - q*q)) / ( ( (m_sigma*m_sigma - q*q)*(1.0 - lambda*Xi) - (g_spp*g_spp*Xi) ) * 1.0/(8.0 * EvtConst::pi * f_pi*f_pi) * q * q );
134
135 EvtComplex B_over_A;
136 B_over_A = EvtComplex(ReB_over_A, ImB_over_A);
137
138 // The dGamma/d(M_pipi) spectrum
139 EvtComplex dGdMpp;
140
141 dGdMpp = abs2((q*q*F - B_over_A)) * q * sqrt(q*q - 4 * m_pi *m_pi) * sqrt(EV2 * EV2 - MV2*MV2);
142
143
144 setProb( real(dGdMpp) );
145 return ;
146
147}
148
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151