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// G4MuonDecayChannelWithSpin
//
// Class decription:
//
// This class describes muon decay kinematics.
// It assumes V-A coupling with 1st order radiative corrections, the
// standard model parameter values, but gives incorrect energy spectrum
// for neutrinos.
// References:
// - Florian Scheck "Muon Physics", in Physics Reports
//   (Review Section of Physics Letters) 44, No. 4 (1978)
//   187-248. North-Holland Publishing Company, Amsterdam at page 210 cc.
// - W.E. Fisher and F. Scheck, Nucl. Phys. B83 (1974) 25.

// Authors: P.Gumplinger and T.MacPhail, 17 August 2004 
// --------------------------------------------------------------------
#ifndef G4MuonDecayChannelWithSpin_hh
#define G4MuonDecayChannelWithSpin_hh 1

#include <CLHEP/Units/PhysicalConstants.h>

#include "globals.hh"
#include "G4ThreeVector.hh"
#include "G4MuonDecayChannel.hh"

class G4MuonDecayChannelWithSpin : public G4MuonDecayChannel
{
  public:

    G4MuonDecayChannelWithSpin(const G4String& theParentName,
                                     G4double  theBR);
    virtual ~G4MuonDecayChannelWithSpin();

    virtual G4DecayProducts* DecayIt(G4double);

  protected:

    G4MuonDecayChannelWithSpin(const G4MuonDecayChannelWithSpin&);
    G4MuonDecayChannelWithSpin& operator=(const G4MuonDecayChannelWithSpin&);
      // Copy constructor and assignment operator
  
  private:

    G4MuonDecayChannelWithSpin();

    // Radiative Correction Factors

    inline G4double F_c(G4double x, G4double x0, G4double omega);
    inline G4double F_theta(G4double x, G4double x0, G4double omega);
    G4double R_c(G4double x, G4double omega);
};

// ------------------------
// Inline methods
// ------------------------

inline G4double
G4MuonDecayChannelWithSpin::F_c(G4double x, G4double x0, G4double omega)
{
  G4double f_c;

  f_c = (5.+17.*x-34.*x*x)*(omega+std::log(x))-22.*x+34.*x*x;
  f_c = (1.-x)/(3.*x*x)*f_c;
  f_c = (6.-4.*x)*R_c(x,omega)+(6.-6.*x)*std::log(x) + f_c;
  f_c = (CLHEP::fine_structure_const/CLHEP::twopi) * (x*x-x0*x0) * f_c;

  return f_c;
}

inline G4double
G4MuonDecayChannelWithSpin::F_theta(G4double x, G4double x0, G4double omega)
{
  G4double f_theta;

  f_theta = (1.+x+34*x*x)*(omega+std::log(x))+3.-7.*x-32.*x*x;
  f_theta = f_theta + ((4.*(1.-x)*(1.-x))/x)*std::log(1.-x);
  f_theta = (1.-x)/(3.*x*x) * f_theta;
  f_theta = (2.-4.*x)*R_c(x,omega)+(2.-6.*x)*std::log(x)-f_theta;
  f_theta = (CLHEP::fine_structure_const/CLHEP::twopi) * (x*x-x0*x0) * f_theta;

  return f_theta;
}

#endif