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/pionNucleon [ Modules ]

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module pionNucleon


Includes the cross sections for pion-nucleon scattering in the resonance regime.

Implemented are the following reactions:

  • pion nucleon -> X

pionNucleon/matrixDeltaEta [ Global module-variables ]

[ Top ] [ pionNucleon ] [ Global module-variables ]


  real, parameter :: matrixDeltaEta=7.


Matrix Element for pi N -> eta Delta ; see old "commcoll"->matdeta

pionNucleon/pionNuc [ Subroutines ]

[ Top ] [ pionNucleon ] [ Subroutines ]


subroutine pionNuc(srts, partIn, mediumAtColl, momLRF, partOut, sigmaTot, sigmaElast, plotFlag, sigmaArr)


Evaluates pion Nucleon -> anything cross sections and returns also a "preevent"

This routine does a Monte-Carlo-decision according to the partial cross sections to decide on a final state with maximal 3 (or 4) final state particles. These are returned in the vector partOut. The kinematics of these particles is only fixed in the case of a single produced resonance. Otherwise the kinematics still need to be established.


  • real :: srts -- sqrt(s) in the process (free one!!)
  • type(particle),dimension(1:2) :: partIn -- colliding particles
  • type(medium) :: mediumAtColl -- Medium information at the position of the collision
  • real, dimension(0:3) :: momLRF -- total momentum in LRF
  • logical, OPTIONAL :: plotFlag -- Switch on plotting of the Xsections


  • real :: sigmaTot -- total Xsection
  • real :: sigmaElast -- elastic Xsection
  • type(preEvent),dimension(1:4) :: partOut -- outgoing particles
  • real, dimension(20), optional :: sigmaArr -- partial cross sections


Possible final states are :

  • 1-particle: baryon Resonances
  • 2-particle: pi N, omega N, phi N, eta Delta, Kaon Lambda , Sigma Kaon, pion Delta, rho N, rhoDelta, sigma N, pion P11_1440, rho Delta
  • 3-particle: omega pi N, phi pi N, K KBar N, Lambda Kaon Pion, Sigma Kaon Pion, pi pi N
  • 4-particle: pi pi pi N
  • pi N -> pi pi N and pi N -> pi pi pi N are used for the matching to the high energy region

pionNuc/evaluateXsections [ Subroutines ]

[ Top ] [ pionNuc ] [ Subroutines ]


subroutine evaluateXsections


Evaluates all Xsections for pi N scattering

pionNuc/makeDecision [ Subroutines ]

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subroutine MakeDecision


Decides on the final state which is returned via partOut by Monte-Carlo.

  * Assigns charges and ID's.
  * Only for resonance-production also the mass is assigned, since the mass
    of the resonance needed to be calculated earlier.

The Monte-Carlo routine is adding up channels until the sum is exceeding x*sigma(total). x has a flat distribution in [0,1]. The last added channel is then the one which is chosen for the event.

pionNuc/makeOutput [ Subroutines ]

[ Top ] [ pionNuc ] [ Subroutines ]


subroutine makeOutput


Writes several cross sections to file as function of srts and plab [GeV]. Filenames:

  • 'piN_sigTotElast.dat' : sigmaTot, sigmaElast
  • 'piN_strangeProd.dat' : strangeness production
  • 'piN_resProd.dat' : Baryon resonance production
  • 'piN_nonStrange_nuk.dat' : non-strange meson with nucleon in final state
  • 'piN_nonStrange_delta.dat ' : non-strange meson with delta in final state