EPIPROD: program to calculate pseudoscalar meson production by electron-nucleon scattering

James J. Kelly
Department of Physics
University of Maryland
College Park, MD 20742 USA

EPIPROD is a program to calculate or fit observables and response functions for electroproduction of pseudoscalar mesons.  Among the features provided are:

• pion or eta electroproduction
• recoil or target polarization
• single- or multi-dimensional kinematical grids
• models:
  • semi-realistic unitary isobar model
  • SAID
  • MAID, DMT, SL, or other external model using interpolation within tabulated multipole amplitudes
• many conversion routines to transform between alternative representations of reaction amplitudes
• numerous options for definitions of response functions, polarization bases, and other conventions
• fitting experimental data using Legendre expansions of response functions
• fitting multipole amplitudes to experimental data for many quantities simultaneously
• fitting response functions to the azimuthal and/or epsilon dependence of cross section and/or polarization data
• L/T using parallel kinematics
• pseudodata testing
• project Legendre or multipole amplitudes from model calculations
• interface for use within Monte Carlo event generators

The current version is 5.4 and was released on July 22, 2005.

A relatively complete manual describing the formalism for the reaction and the use of most program features is available.  Some of the formalism used by EPIPROD was developed using the following Mathematica notebooks, which are available as either notebook (*.nb) or postscript (*.ps) files.

• RecoilPolarization:      nb      ps
• TargetPolarization:      nb      ps

Installation instructions

The current version of EPIPROD source files can be downloaded in the form of a self-extracting archive file by clicking on epiprod. The files were archived using tar, compressed with gzip, and encoded using uuencode. On unix systems, the following steps

1. strip any mailer junk
2. chmod 744 epiprod.uu
3. epiprod.uu

will produce a set of source files and subdirectories.  In subdirectory ./LIB you will find a Makefile that directs compilation and linking of a set of library routines.  You will need to define the environment variable epidir pointing to the program's top directory.  Depending upon your computer system, you may need to adjust some of the compiler options.  EPIPROD also requires a separate library called jjklib that contains subprograms shared with several other of my programs. 

EPIPROD comes with several sample input files in the subdirectory ./SAMPLES. Please verify that these cases run correctly. You are now ready to proceed.

Revision history

EPIPROD was originally written by T. E. Payerle, as my student, based in part upon an earlier program by R. W. Lourie but with corrections and considerably expanded capabilities. Version 2.3.6 is the last version with which Payerle was involved. Version 3 represents an extensive rewriting of EPIPROD in an effort to generalize the formalism to permit eventual application to electroproduction of any pseudoscalar meson.  Eta production became available in Version 3.0, Monte Carlo event generation in Version 4.0, and data analysis procedures in Version 5.0.  Further details on the revision history and archival versions can be found at history.  However, new users are strongly advised to begin with the current version and to check periodically for updates.  

Disclaimer

This material is distributed free of charge for research purposes and carries no express or implied warranties. You may install these routines and may make whatever modifications are required for any noncommercial application, provided that proper acknowledgment is given in custom versions and in publications, but support will be provided only for approved versions. Please notify me of any errors that are found or extensions that are needed.

Please report errors or problems to: James J. Kelly
Last revised: July 22, 2005