Re: problems with initialising Pythia

From: Rene Brun (Rene.Brun@cern.ch)
Date: Fri Jan 22 1999 - 11:39:08 MET


Robert Loke wrote:
> 
> Hi Rooters,
> 
> I've got a problem in intializing Pythia:
> 
> ======== source code ===========
> TROOT PythRoot("PythRoot","running pythia");
> 
> int main(){
> 
>   //inits
>   int NofEvents = 100;
>   TPythia pythia;
>   TObjArray* particlelist;
> 
>   TFile ofile("pythia.root","RECREATE");
> 
>   pythia.SetMSEL(1);
>   pythia.SetPMAS(6,1,175.0);
> 
>   pythia.Initialize("FIXT","p","p",820.);
> 
> (...)
> }
> 

Hi Robert,
When I run your example with the standard Root and the following
interactive session dynamically linking with the Pythia libraries,
I obtain a correct result, see below.
I use an old version of Pythia (5.7) because I was told that there are 
problems with version 6.

Rene Brun

root [0] gSystem.Load("libEG")
(int)0
root [1] gSystem.Load("$PYTHIA/libPythia")
(int)0
root [2] gSystem.Load("libEGPythia")
(int)0
root [3] TPythia pythia;
root [4] pythia.SetMSEL(1);
root [5] pythia.SetPMAS(6,1,175.0);
root [6] pythia.Initialize("FIXT","p","p",820.);
1                                                                              

******************************************************************************

******************************************************************************

**                                                                         
**

**                                                                         
**
 **  PPP  Y   Y TTTTT H   H III   A        JJJJ EEEE TTTTT  SSS  EEEE
TTTTT  **
 **  P  P  Y Y    T   H   H  I   A A          J E      T   S     E     
T    **
 **  PPP    Y     T   HHHHH  I  AAAAA         J EEE    T    SSS  EEE   
T    **
 **  P      Y     T   H   H  I  A   A      J  J E      T       S E     
T    **
 **  P      Y     T   H   H III A   A       JJ  EEEE   T    SSS  EEEE  
T    **

**                                                                         
**

**                                                                         
**
 **              *......*                  Welcome to the Lund Monte
Carlo!  **
 **        
*:::!!:::::::::::*                                               **
 **      *::::::!!::::::::::::::*            This is PYTHIA version
5.707    **
 **    *::::::::!!::::::::::::::::*        Last date of change: 20 Oct
1994  **
 **  
*:::::::::!!:::::::::::::::::*                                        
**
 **   *:::::::::!!:::::::::::::::::*         This is JETSET version
7.401    **
 **    *::::::::!!::::::::::::::::*!       Last date of change: 11 Feb
1994  **
 **      *::::::!!::::::::::::::*
!!                                         **
 **      !! *:::!!:::::::::::*   
!!                                         **
 **      !!     !* -><- *         !!                 Main
author:            **
 **      !!     !!                !!              Torbjorn
Sjostrand         **
 **      !!     !!                !!            Theory Division,
CERN,       **
 **      !!                       !!              CH-1211 Geneva
23,         **
 **      !!        ep             !!                
Switzerland             **
 **      !!                       !!          phone +41 - 22 - 767 28
20     **
 **      !!                 pp    !!         E-mail
TORSJO@CERNVM.CERN.CH    **
 **      !!   e+e-               
!!                                         **
 **      !!                       !!         Copyright Torbjorn
Sjostrand    **
 **      !!                                     and CERN, Geneva
1993        **

**                                                                         
**

**                                                                         
**
 ** When you cite these programs, priority should always be given to
the     **
 ** latest published
description.                                            **
 ** Currently this is, for
JETSET                                            **
 ** T. Sjostrand and M. Bengtsson, Computer Physics Commun. 43 (1987)
367,   **
 ** and for
PYTHIA                                                           **
 ** H.-U. Bengtsson and T. Sjostrand, Computer Physics Commun. 46 (1987)
43. **
 ** The most recent long description (unpublished)
is:                       **
 ** T. Sjostrand, CERN-TH.7112/93
(1993).                                    **
 ** Also remember that the programs, to a large extent, represent
original   **
 ** physics research. Other publications of special relevance to
your        **
 ** studies may therefore deserve separate
mention.                          **

**                                                                         
**

**                                                                         
**

******************************************************************************

******************************************************************************

 Warning: JETSET subversion too old for PYTHIA

1****************** PYINIT: initialization of PYTHIA routines
*****************


==============================================================================

I                                                                           
I
 I             PYTHIA will be initialized for p on p fixed
target             I
 I                      at    820.000 GeV/c
lab-momentum                      I

I                                                                           
I
 I           corresponding to     39.250 GeV center-of-mass
energy            I

I                                                                           
I

==============================================================================

 ******** PYMAXI: summary of differential cross-section maximum search
********

           ==========================================================
           I                                      I                 I
           I  ISUB  Subprocess name               I  Maximum value  I
           I                                      I                 I
           ==========================================================
           I                                      I                 I
           I   95   Low-pT scattering             I    2.4146E+01   I
           I   96   Semihard QCD 2 -> 2           I    2.7197E+01   I
           I                                      I                 I
           ==========================================================

 ********************** PYINIT: initialization completed
**********************


> =================================
> 
> The ouput produced is:
> 
>  ******************************************************************************
>  ******************************************************************************
>  **                                                                          **
>  **                                                                          **
>  **              *......*                  Welcome to the Lund Monte Carlo!  **
>  **         *:::!!:::::::::::*                                               **
>  **      *::::::!!::::::::::::::*          PPP  Y   Y TTTTT H   H III   A    **
>  **    *::::::::!!::::::::::::::::*        P  P  Y Y    T   H   H  I   A A   **
>  **   *:::::::::!!:::::::::::::::::*       PPP    Y     T   HHHHH  I  AAAAA  **
>  **   *:::::::::!!:::::::::::::::::*       P      Y     T   H   H  I  A   A  **
>  **    *::::::::!!::::::::::::::::*!       P      Y     T   H   H III A   A  **
>  **      *::::::!!::::::::::::::* !!                                         **
>  **      !! *:::!!:::::::::::*    !!       This is PYTHIA version 6.115      **
>  **      !!     !* -><- *         !!       Last date of change: 27 Jan 1998  **
>  **      !!     !!                !!                                         **
>  **      !!     !!                !!                                         **
>  **      !!                       !!                                         **
>  **      !!        ep             !!       Disclaimer: this program comes    **
>  **      !!                       !!       without any guarantees. Beware    **
>  **      !!                 pp    !!       of errors and use common sense    **
>  **      !!   e+e-                !!       when interpreting results.        **
>  **      !!                       !!                                         **
>  **      !!                                Copyright T. Sjostrand (1997)     **
>  **                                                                          **
>  ** An archive of program versions and documentation is found on the web:    **
>  ** http://www.thep.lu.se/tf2/staff/torbjorn/Pythia.html                     **
>  **                                                                          **
>  ** When you cite this program, currently the official reference is          **
>  ** T. Sjostrand, Computer Physics Commun. 82 (1994) 74.                     **
>  ** The supersymmetry extensions are described in                            **
>  ** S. Mrenna, Computer Physics Commun. 101 (1997) 232                       **
>  ** Also remember that the program, to a large extent, represents original   **
>  ** physics research. Other publications of special relevance to your        **
>  ** studies may therefore deserve separate mention.                          **
>  **                                                                          **
>  ** Main author: Torbjorn Sjostrand; Department of Theoretical Physics 2,    **
>  **   Lund University, Solvegatan 14A, S-223 62 Lund, Sweden;                **
>  **   phone: + 46 - 46 - 222 48 16; e-mail: torbjorn@thep.lu.se              **
>  ** SUSY author: Stephen Mrenna, Argonne National Laboratory,                **
>  **   9700 South Cass Avenue, Argonne, IL 60439, USA;                        **
>  **   phone: + 1 - 630 - 252 - 7615; e-mail: mrenna@hep.anl.gov              **
>  **                                                                          **
>  **                                                                          **
>  ******************************************************************************
>  ******************************************************************************
> 1****************** PYINIT: initialization of PYTHIA routines *****************
> 
>  ==============================================================================
>  I                                                                            I
>  I             PYTHIA will be initialized for p on p fixed target             I
>  I                      at     -1.997 GeV/c lab-momentum                      I
>  I                                                                            I
>  I           corresponding to      2.429 GeV center-of-mass energy            I
>  I                                                                            I
>  ==============================================================================
>  Error: too low CM energy,   2.429 GeV for event generation.
>  Execution stopped!
> -------------------------------------------------------------------------------
> -------------------------------------------------------------------------------
> 
> I compared with the AtlFast-docu on the root-HP, but didn't find the
> difference up to the initialize-call...
> 
> So: what's going wrong?
> 
> I'm running root, version 2.20/06 on LINUX.
> 
> Any help is welcome...
> 
> Thanks, Robert
> 
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> +     Robert Loke                                         +
> +     Humboldt University Berlin                          +
> +     Invalidenstr. 110                                   +
> +     10115 Berlin                                        +
> +     Germany                                             +
> +                                                         +
> +     e-mail : loke@ifh.de                                +
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++



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