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/PhotonPionProduction_medium [ Modules ]

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NAME

module PhotonPionProduction_medium

PURPOSE

  • Evaluates the photon nucleon -> pion nucleon cross section in the medium.
  • Fermi motion of the incoming nucleon, as well as the potentials of the in and outgoing nucleons are taken into account.
  • Always assumes that incoming photon travels in z-direction

PhotonPionProduction_medium/dSigmadOmega_k_med [ Functions ]

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NAME

function dSigmaddOmega_k_med(init_Nuc,pionCharge,energy_li,phi_k,theta_k,q,k,pf) Result(dSigma)

PURPOSE

  • Evaluates the gamma nucleon -> pion nucleon cross section as 2-fold differential dSigma/dOmega(pion).
  • This is done using the formulas which include explicitly H_mu nu g^mu nu.
  • The angles of the outgoing pion are measured relative to the photon momentum "q"
  • Result in units of mb/sr .

INPUTS

  • type(particle),intent(in) :: init_Nuc ! incoming nucleon in the frame where electron runs in +z direction
  • integer, intent(in) :: pionCharge ! charge of outgoing pion
  • real, intent(in) :: phi_k, theta_k ! pion scattering angles in units of DEGREE with respect to momentum transfer q
  • real, intent(in), dimension(0:3) :: q ! photon 4-momentum

RESULT

  • real :: dSigma ! dsigma/dOmega(final pion)
  • real, intent(out), dimension(0:3) :: pf ! outgoing nucleon 4-momentum
  • real, intent(out), dimension(0:3) :: k ! outgoing pion 4-momentum

PhotonPionProduction_medium/getKinematics_photon [ Subroutines ]

[ Top ] [ PhotonPionProduction_medium ] [ Subroutines ]

NAME

subroutine getKinematics_photon(pionCharge,initNuc,phi_k,theta_k,q,k,pf,success)

PURPOSE

Evaluates the full kinematics for a gamma nucleon -> pion nucleon reaction.

The angles of the outgoing pion are measured relative to the momentum transfer "q". All angles in degree.

INPUTS

  • real,intent(in) :: phi_k, theta_k ! pion scattering angles in units of degree
  • type(particle), intent(in) :: initNuc ! initial nucleon

RESULT

  • real, dimension(0:3), intent(out) :: k,q,pf
  • 4-momenta of pion, photon and final nucleon in [GeV]
  • logical, intent(out) :: success ! Flag shows whether the kinematics could be established. .true.=success, .false.=no success