include/Geant4/G4MuonDecayChannelWithSpin.hh

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0025 //
0026 // G4MuonDecayChannelWithSpin
0027 //
0028 // Class decription:
0029 //
0030 // This class describes muon decay kinematics.
0031 // It assumes V-A coupling with 1st order radiative corrections, the
0032 // standard model parameter values, but gives incorrect energy spectrum
0033 // for neutrinos.
0034 // References:
0035 // - Florian Scheck "Muon Physics", in Physics Reports
0036 //   (Review Section of Physics Letters) 44, No. 4 (1978)
0037 //   187-248. North-Holland Publishing Company, Amsterdam at page 210 cc.
0038 // - W.E. Fisher and F. Scheck, Nucl. Phys. B83 (1974) 25.
0039
0040 // Authors: P.Gumplinger and T.MacPhail, 17 August 2004
0041 // --------------------------------------------------------------------
0042 #ifndef G4MuonDecayChannelWithSpin_hh
0043 #define G4MuonDecayChannelWithSpin_hh 1
0044
0045 #include "G4MuonDecayChannel.hh"
0046 #include "G4ThreeVector.hh"
0047 #include "globals.hh"
0048
0049 #include <CLHEP/Units/PhysicalConstants.h>
0050
0051 class G4MuonDecayChannelWithSpin : public G4MuonDecayChannel
0052 {
0053   public:
0054     G4MuonDecayChannelWithSpin(const G4String& theParentName, G4double theBR);
0055     ~G4MuonDecayChannelWithSpin() override = default;
0056
0057     G4DecayProducts* DecayIt(G4double) override;
0058
0059   protected:
0060     // Copy constructor and assignment operator
0061     G4MuonDecayChannelWithSpin(const G4MuonDecayChannelWithSpin&) = default;
0062     G4MuonDecayChannelWithSpin& operator=(const G4MuonDecayChannelWithSpin&);
0063
0064   private:
0065     G4MuonDecayChannelWithSpin() = default;
0066
0067     // Radiative Correction Factors
0068     inline G4double F_c(G4double x, G4double x0, G4double omega);
0069     inline G4double F_theta(G4double x, G4double x0, G4double omega);
0070     G4double R_c(G4double x, G4double omega);
0071 };
0072
0073 // ------------------------
0074 // Inline methods
0075 // ------------------------
0076
0077 inline G4double G4MuonDecayChannelWithSpin::F_c(G4double x, G4double x0, G4double omega)
0078 {
0079   G4double f_c;
0080
0081   f_c = (5. + 17. * x - 34. * x * x) * (omega + std::log(x)) - 22. * x + 34. * x * x;
0082   f_c = (1. - x) / (3. * x * x) * f_c;
0083   f_c = (6. - 4. * x) * R_c(x, omega) + (6. - 6. * x) * std::log(x) + f_c;
0084   f_c = (CLHEP::fine_structure_const / CLHEP::twopi) * (x * x - x0 * x0) * f_c;
0085
0086   return f_c;
0087 }
0088
0089 inline G4double G4MuonDecayChannelWithSpin::F_theta(G4double x, G4double x0, G4double omega)
0090 {
0091   G4double f_theta;
0092
0093   f_theta = (1. + x + 34 * x * x) * (omega + std::log(x)) + 3. - 7. * x - 32. * x * x;
0094   f_theta = f_theta + ((4. * (1. - x) * (1. - x)) / x) * std::log(1. - x);
0095   f_theta = (1. - x) / (3. * x * x) * f_theta;
0096   f_theta = (2. - 4. * x) * R_c(x, omega) + (2. - 6. * x) * std::log(x) - f_theta;
0097   f_theta = (CLHEP::fine_structure_const / CLHEP::twopi) * (x * x - x0 * x0) * f_theta;
0098
0099   return f_theta;
0100 }
0101
0102 #endif