Using Pythia 6.x in Run 1

Our version of Pythia 6 is nearly a drop-in replacement for the Pythia 5.6 that comes with the Run 1 distribution. It can, in fact, be linked in to an analysis_control job using the same dictionary file as the 5.6 version.

Installing the binary version

  1. Download pythia6.tar.gz, which contains the files libpythia6.a, libpythiaMods.a, libpythiaR_N.a, libpythianull.a, cvtable6.dbt, and pyttlk6.uid.
  2. Place cvtable6.dbt and pyttlk6.uid in your $PYTHIA_LIBRARY directory.
  3. Place all the .a files in your $CDFSOFT1_DIR/lib/Linux2-????/ directory.

Using Pythia 6

The dictionary file from the pythia5_6 directory can be used with Pythia 6.

What's in each file?

Upgrading Pythia

The version of Pythia above is 6.156. To upgrade, get the latest code from the Pythia homepage. Comment out or delete the functions/subroutines PYR, PDFSET, PYUPIN, PYUPEV, STRUCTM, and STRUCTP. Then execute

g77 -c pythia6xxx.f -O2
ar r path-to-libpythia6.a pythia6xxx.o 
Then recompile your programs.

Installing the source version

Download run1pythia.tar.gz and untar. Change to the directory run1pythia and type make. This should create the four libraries. Typing make install should then place them in appropriate directories.

Known issues

The talk_to continues to refer to "JETSET", even though it doesn't exist as a separate program anymore. For a translation key between the old and new variable names (e.g. LUDATA2 -> PYDATA2), see the update notes for Pythia.

The defaults for fragmentation have changed between Pythia 5.6 and 6.152. See the Run II note and the "UNDERLYING EVENTS" section of the Pythia update notes for more information. (Rest assured, π0 decay was turned back on in 6.130 :-))

Finally, the decay table numbering has changed.


8/18/00: Merged in Jeff Berryhill's code for SPYTHIA. The talk_to now recognizes the supersymmetry process numbers, and can set the supersymmetry parameters. See CDF Note 3794 for a manual. In addition, we now use the R_N package to generate random numbers.

9/28/00: Upgraded to Pythia 6.152. Gave up on the shared library idea; it was too painful to maintain it. Updated the page with the new download and link procedures.

10/5/00: Source code actually compiles now. Upgraded to Pythia 6.154.

11/20/00: Updated to Pythia 6.156.

Created 7/20/00, Peter Onyisi (
Last updated 11/20/00, PO