6.5.4. Kinematic-fitting convenience functions

The Orca kinematic fitter is a global fitting tool.

A typical use-case would be to to constrain the 4-momentum of all particles provided to the 4-momentum of the beam. This is a “4C” fit (four constraints).

Note

By default, the 4-momentum of the beam is taken without uncertainties.

kinfit.MassfitKinematic1C(list_name, invMass, fitterEngine='NewFitterGSL', constraint='Mass', daughtersUpdate=True, path=None)[source]

Perform recoil mass kinematic fit for particles in the given ParticleList.

Parameters

  • list_name – name of the input ParticleList

  • fitterEngine – which fitter engine to use? ‘NewFitterGSL’ or ‘OPALFitterGSL’

  • constraint – HardBeam or RecoilMass or Mass

  • invMass – Invariant Mass (GeV)

  • daughtersUpdate – make copy of the daughters and update them after the vertex fit

  • path – modules are added to this path

kinfit.MassfitKinematic1CRecoil(list_name, recoilMass, fitterEngine='NewFitterGSL', constraint='RecoilMass', daughtersUpdate=True, path=None)[source]

Perform recoil mass kinematic fit for particles in the given ParticleList.

Parameters

  • list_name – name of the input ParticleList

  • fitterEngine – which fitter engine to use? ‘NewFitterGSL’ or ‘OPALFitterGSL’

  • constraint – HardBeam or RecoilMass

  • recoilMass – RecoilMass (GeV)

  • daughtersUpdate – make copy of the daughters and update them after the vertex fit

  • path – modules are added to this path

kinfit.UnmeasuredfitKinematic1C(list_name, fitterEngine='NewFitterGSL', constraint='HardBeam', daughtersUpdate=True, path=None)[source]

Perform 1C momentum constraint kinematic fit with one unmeasured photon for particles in the given ParticleList.

Parameters

  • list_name – name of the input ParticleList

  • fitterEngine – which fitter engine to use? ‘NewFitterGSL’ or ‘OPALFitterGSL’

  • constraint – HardBeam or RecoilMass

  • daughtersUpdate – make copy of the daughters and update them after the vertex fit

  • path – modules are added to this path

kinfit.fitKinematic3C(list_name, fitterEngine='NewFitterGSL', constraint='HardBeam', daughtersUpdate=True, addUnmeasuredPhoton=False, add3CPhoton=True, path=None)[source]

Perform 3C momentum constraint kinematic fit with one photon with unmeasured energy for particles in the given ParticleList, the first daughter should be the energy unmeasured Photon.

Parameters

  • list_name – name of the input ParticleList

  • fitterEngine – which fitter engine to use? ‘NewFitterGSL’ or ‘OPALFitterGSL’

  • constraint – HardBeam or RecoilMass

  • daughtersUpdate – make copy of the daughters and update them after the vertex fit

  • addUnmeasuredPhoton – add one unmeasured photon (uses up three constraints)

  • add3CPhoton – add one photon with unmeasured energy (uses up a constraint)

  • path – modules are added to this path

kinfit.fitKinematic4C(list_name, fitterEngine='NewFitterGSL', constraint='HardBeam', daughtersUpdate=True, addUnmeasuredPhoton=False, path=None)[source]

Perform a 4C momentum constraint kinematic fit for particles in the given ParticleList.

Parameters

  • list_name – name of the input ParticleList

  • fitterEngine – which fitter engine to use? ‘NewFitterGSL’ or ‘OPALFitterGSL’

  • constraint – HardBeam or RecoilMass

  • daughtersUpdate – make copy of the daughters and update them after the vertex fit

  • addUnmeasuredPhoton – add one unmeasured photon (uses up three constraints)

  • path – modules are added to this path