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da0e9ce3 | 1 | //----------------------------------------------------------------------- |
2 | // File and Version Information: | |
3 | // | |
4 | // Copyright Information: See EvtGen/COPYRIGHT | |
5 | // | |
6 | // | |
7 | // Description: | |
8 | // DFN model: | |
9 | // F(k+) = N (1-x)^a exp((1+a)x) ,x=k+/(mB-mb) | |
10 | // the fermi motion distribution according to | |
11 | // hep-ph/9905351 v2 | |
12 | // BLNP model: | |
13 | // F(wtilde,Lambda,b) = pow(_b,_b)/(tgamma(_b)*_Lambda)*pow(wtilde/_Lambda,_b-1)* | |
14 | // exp(-_b*wtilde/Lambda); | |
15 | // the leading order shape function (exp) (hep-ph/0504071) | |
16 | // Environment: | |
17 | // Software developed for the BaBar Detector at the SLAC B-Factory. | |
18 | // | |
19 | // Author List: | |
20 | // Sven Menke (DFN model) | |
21 | // Alexei Volk (BLNP model) | |
22 | //----------------------------------------------------------------------- | |
23 | //----------------------- | |
24 | // This Class's Header -- | |
25 | //----------------------- | |
26 | #include "EvtGenBase/EvtPatches.hh" | |
27 | #include "EvtGenModels/EvtPFermi.hh" | |
28 | #include "EvtGenBase/EvtReport.hh" | |
29 | //--------------- | |
30 | // C Headers -- | |
31 | //--------------- | |
32 | #include <math.h> | |
33 | #include <stdlib.h> | |
34 | ||
35 | //---------------- | |
36 | // Constructors -- | |
37 | //---------------- | |
38 | ||
39 | //for DFN model | |
40 | EvtPFermi::EvtPFermi(const double &a, const double &mB, const double &mb) | |
41 | { | |
42 | _a = a; | |
43 | _mb = mb; | |
44 | _mB = mB; | |
45 | } | |
46 | ||
47 | // for BLNP modell | |
48 | EvtPFermi::EvtPFermi(const double &Lambda, const double &b) | |
49 | { | |
50 | _Lambda = Lambda; | |
51 | _b = b; | |
52 | } | |
53 | ||
54 | ||
55 | //-------------- | |
56 | // Destructor -- | |
57 | //-------------- | |
58 | ||
59 | EvtPFermi::~EvtPFermi( ) | |
60 | { | |
61 | } | |
62 | ||
63 | //----------- | |
64 | // Methods -- | |
65 | //----------- | |
66 | ||
67 | double EvtPFermi::getFPFermi(const double &kplus) | |
68 | { | |
69 | double FKplus; | |
70 | double x = kplus/(_mB-_mb); | |
71 | ||
72 | if ( x >= 1) return 0; | |
73 | if ( kplus <= -_mb) return 0; | |
74 | ||
75 | FKplus = pow(1-x,_a)*exp((1+_a)*x); | |
76 | ||
77 | return FKplus; | |
78 | } | |
79 | ||
80 | // get value for the leading order exponential SF | |
81 | double EvtPFermi::getSFBLNP(const double &what) | |
82 | { | |
83 | double SF; | |
84 | double massB = 5.2792; | |
85 | ||
86 | ||
87 | if ( what > massB ) return 0; | |
88 | if ( what < 0 ) return 0; | |
89 | ||
90 | #if defined(__SUNPRO_CC) | |
91 | report(ERROR,"EvtGen") << "The tgamma function is not available on this platform\n"; | |
92 | report(ERROR,"EvtGen") <<"Presumably, you are getting the wrong answer, so I abort.."; | |
93 | ::abort(); | |
94 | #else | |
95 | SF = pow(_b,_b)/(tgamma(_b)*_Lambda)*pow(what/_Lambda,_b-1)*exp(-_b*what/_Lambda); | |
96 | #endif | |
97 | ||
98 | return SF; | |
99 | } | |
100 |