PYTHIA  8.303
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HMEHiggs2TwoFermions Class Reference

Helicity matrix element for the decay of a Higgs -> two fermions. More...

#include <HelicityMatrixElements.h>

Inheritance diagram for HMEHiggs2TwoFermions:
HelicityMatrixElement

Public Member Functions

void initConstants ()
 Helicity matrix element for the decay of a Higgs to two fermions. More...
 
void initWaves (vector< HelicityParticle > &)
 Initialize wave functions for the helicity matrix element.
 
complex calculateME (vector< int >)
 Return element for the helicity matrix element.
 
- Public Member Functions inherited from HelicityMatrixElement
 HelicityMatrixElement ()
 Constructor and destructor.
 
virtual void initPointers (ParticleData *, CoupSM *, Settings *=0)
 Initialize the physics matrices and pointers. More...
 
virtual HelicityMatrixElementinitChannel (vector< HelicityParticle > &)
 Initialize the channel. More...
 
virtual double decayWeight (vector< HelicityParticle > &)
 Calculate the matrix element weight for a decay. More...
 
virtual double decayWeightMax (vector< HelicityParticle > &)
 Calculate the maximum matrix element decay weight.
 
virtual void calculateD (vector< HelicityParticle > &)
 Calculate the decay matrix for a particle. More...
 
virtual void calculateRho (unsigned int, vector< HelicityParticle > &)
 Calculate the density matrix for a particle. More...
 
void setFermionLine (int, HelicityParticle &, HelicityParticle &)
 Set a fermion line. More...
 
virtual complex breitWigner (double s, double M, double G)
 Calculate Breit-Wigner's with running widths and fixed. More...
 
virtual complex sBreitWigner (double m0, double m1, double s, double M, double G)
 Return an s-wave BreitWigner.
 
virtual complex pBreitWigner (double m0, double m1, double s, double M, double G)
 Return a p-wave BreitWigner.
 
virtual complex dBreitWigner (double m0, double m1, double s, double M, double G)
 Return a d-wave BreitWigner.
 

Additional Inherited Members

- Protected Attributes inherited from HelicityMatrixElement
double DECAYWEIGHTMAX
 Maximum decay weight. WARNING: hardcoded constant.
 
vector< GammaMatrixgamma
 Physics matrices.
 
vector< int > pMap
 Particle map vector.
 
vector< int > pID
 Particle ID vector.
 
vector< double > pM
 Particle mass vector.
 
vector< vector< Wave4 > > u
 Wave functions.
 
ParticleDataparticleDataPtr
 Pointer to particle data.
 
CoupSMcoupSMPtr
 Pointer to Standard Model constants.
 
SettingssettingsPtr
 Pointer to Settings.
 

Detailed Description

Helicity matrix element for the decay of a Higgs -> two fermions.

Because the Higgs is spin zero the Higgs production mechanism is not needed for calculating helicity density matrices. However, the CP mixing is needed.

Member Function Documentation

void initConstants ( )
virtual

Helicity matrix element for the decay of a Higgs to two fermions.

All SM and MSSM Higgses couple to fermions with a vertex factor of (pfCV - pfCA * gamma[5]) where pf indicates the type of fermion line. For simplicity for the SM and MSSM CP even Higgses pfCV is set to one, and pfCA to zero, as this matrix element is used only for calculating helicity density matrices. p2CA: in the SM/MSSM this coupling is zero for CP-even and for CP-odd: -g_w * m_f / (2 * m_W)

  • cot(beta) for A^0 u-type
  • tan(beta) for A^0 d-type p2CA: for the charged Higgs in the MSSM this coupling is given by: +/- i * g / (sqrt(8.) * m_W) * (m_d * tan(beta) - m_u * cot(beta)) p2CV: in the SM/MSSM this coupling is zero for CP-odd and for CP-even: i * g_w * m_f / (2 * m_W)
    • -1 for the SM H
    • -sin(alpha) / sin(beta) for H^0 u-type
    • -cos(alpha) / cos(beta) for H^0 d-type
    • -cos(alpha) / sin(beta) for h^0 u-type
    • sin(alpha) / cos(beta) for h^0 d-type p2CV: for the charged Higgs in the MSSM this coupling is given by: i * g / (sqrt(8.) * m_W) * (m_d * tan(beta) + m_u * cot(beta)) Initialize the constant for the helicity matrix element.

Set the H4 constants.

Neutral constants; settings available.

Set the H1 mixing.

Set the H2 mixing.

Set the A3 mixing.

Neutral constants; default SM/MSSM.

Reimplemented from HelicityMatrixElement.


The documentation for this class was generated from the following files: