### TABLE OF CONTENTS

- 1. /pionNucleon
- 1.1. pionNucleon/matrixDeltaEta
- 1.2. pionNucleon/pionNuc
- 1.2.1. pionNuc/evaluateXsections
- 1.2.2. pionNuc/makeDecision
- 1.2.3. pionNuc/makeOutput

## /pionNucleon [ Modules ]

NAME

module **pionNucleon**

PURPOSE

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 ]

SOURCE

real, parameter ::matrixDeltaEta=7.

PURPOSE

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

## pionNucleon/pionNuc [ Subroutines ]

[ Top ] [ pionNucleon ] [ Subroutines ]

NAME

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

PURPOSE

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.

INPUTS

- 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

RESULT

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

NOTES

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 ]

NAME

subroutine **evaluateXsections**

PURPOSE

Evaluates all Xsections for pi N scattering

## pionNuc/makeDecision [ Subroutines ]

[ Top ] [ pionNuc ] [ Subroutines ]

NAME

subroutine MakeDecision

PURPOSE

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 ]

NAME

subroutine **makeOutput**

PURPOSE

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