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G4MuonDecayChannelWithSpin.hh
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25 //
26 // ------------------------------------------------------------
27 // GEANT 4 class header file
28 //
29 // History:
30 // 17 August 2004 P.Gumplinger and T.MacPhail
31 // samples Michel spectrum including 1st order
32 // radiative corrections
33 // Reference: Florian Scheck "Muon Physics", in Physics Reports
34 // (Review Section of Physics Letters) 44, No. 4 (1978)
35 // 187-248. North-Holland Publishing Company, Amsterdam
36 // at page 210 cc.
37 //
38 // W.E. Fisher and F. Scheck, Nucl. Phys. B83 (1974) 25.
39 //
40 // ------------------------------------------------------------
41 #ifndef G4MuonDecayChannelWithSpin_hh
42 #define G4MuonDecayChannelWithSpin_hh 1
43 
45 
46 #include "globals.hh"
47 #include "G4ThreeVector.hh"
48 #include "G4MuonDecayChannel.hh"
49 
51 {
52  // Class Decription
53  // This class describes muon decay kinemtics.
54  // This version assumes V-A coupling with 1st order radiative correctons,
55  // the standard model Michel parameter values, but
56  // gives incorrect energy spectrum for neutrinos
57 
58 public: // With Description
59 
60  //Constructors
61  G4MuonDecayChannelWithSpin(const G4String& theParentName,
62  G4double theBR);
63  // Destructor
65 
66 protected:
67  // Copy constructor and assignment operator
70 
71 private:
73 
74 public: // With Description
75 
77 
79  const G4ThreeVector& GetPolarization() const;
80 
81 private:
82 
83  G4ThreeVector parent_polarization;
84 
85 // Radiative Correction Factors
86 
87  G4double F_c(G4double x, G4double x0);
88  G4double F_theta(G4double x, G4double x0);
89  G4double R_c(G4double x);
90 
91  G4double EMMU;
92  G4double EMASS;
93 
94 };
95 
97 {
98  parent_polarization = polar;
99 }
100 
102 {
103  return parent_polarization;
104 }
105 
106 inline G4double G4MuonDecayChannelWithSpin::F_c(G4double x, G4double x0)
107 {
108  G4double omega = std::log(EMMU/EMASS);
109 
110  G4double f_c;
111 
112  f_c = (5.+17.*x-34.*x*x)*(omega+std::log(x))-22.*x+34.*x*x;
113  f_c = (1.-x)/(3.*x*x)*f_c;
114  f_c = (6.-4.*x)*R_c(x)+(6.-6.*x)*std::log(x) + f_c;
115  f_c = (CLHEP::fine_structure_const/CLHEP::twopi) * (x*x-x0*x0) * f_c;
116 
117  return f_c;
118 }
119 
120 inline G4double G4MuonDecayChannelWithSpin::F_theta(G4double x, G4double x0)
121 {
122  G4double omega = std::log(EMMU/EMASS);
123 
124  G4double f_theta;
125 
126  f_theta = (1.+x+34*x*x)*(omega+std::log(x))+3.-7.*x-32.*x*x;
127  f_theta = f_theta + ((4.*(1.-x)*(1.-x))/x)*std::log(1.-x);
128  f_theta = (1.-x)/(3.*x*x) * f_theta;
129  f_theta = (2.-4.*x)*R_c(x)+(2.-6.*x)*std::log(x)-f_theta;
130  f_theta = (CLHEP::fine_structure_const/CLHEP::twopi) * (x*x-x0*x0) * f_theta;
131 
132  return f_theta;
133 }
134 
135 #endif