Pythia8 produces empty file after reading LHE file

[Dennis Arogancia]

Hi,

I recently installed Madgraph 2.7.2. I'm using Pythia v8.244 to shower the LHE events however it generated an empty file. I followed the suggestion in this thread: "265962: Pythia8 reading problem LHE file generated by MG5_aMC" and changed the LHE version to 2.0 but still it produces an empty hepmc file. Here is the error log in pythia:

 *------------------------------------------------------------------------------------*
 | |
 | *------------------------------------------------------------------------------* |
 | | | |
 | | | |
 | | PPP Y Y TTTTT H H III A Welcome to the Lund Monte Carlo! | |
 | | P P Y Y T H H I A A This is PYTHIA version 8.244 | |
 | | PPP Y T HHHHH I AAAAA Last date of change: 20 Dec 2019 | |
 | | P Y T H H I A A | |
 | | P Y T H H III A A Now is 29 Apr 2020 at 22:52:54 | |
 | | | |
 | | Christian Bierlich; Department of Astronomy and Theoretical Physics, | |
 | | Lund University, Solvegatan 14A, SE-223 62 Lund, Sweden; | |
 | | e-mail: <email address hidden> | |
 | | Nishita Desai; Department of Theoretical Physics, Tata Institute, | |
 | | Homi Bhabha Road, Mumbai 400005, India; | |
 | | e-mail: <email address hidden> | |
 | | Ilkka Helenius; Department of Physics, University of Jyvaskyla, | |
 | | P.O. Box 35, FI-40014 University of Jyvaskyla, Finland; | |
 | | e-mail: <email address hidden> | |
 | | Philip Ilten; School of Physics and Astronomy, | |
 | | University of Birmingham, Birmingham, B152 2TT, UK; | |
 | | e-mail: <email address hidden> | |
 | | Leif Lonnblad; Department of Astronomy and Theoretical Physics, | |
 | | Lund University, Solvegatan 14A, SE-223 62 Lund, Sweden; | |
 | | e-mail: <email address hidden> | |
 | | Stephen Mrenna; Computing Division, Simulations Group, | |
 | | Fermi National Accelerator Laboratory, MS 234, Batavia, IL 60510, USA; | |
 | | e-mail: <email address hidden> | |
 | | Stefan Prestel; Department of Astronomy and Theoretical Physics, | |
 | | Lund University, Solvegatan 14A, SE-223 62 Lund, Sweden; | |
 | | e-mail: <email address hidden> | |
 | | Christine O. Rasmussen; Department of Astronomy and Theoretical Physics, | |
 | | Lund University, Solvegatan 14A, SE-223 62 Lund, Sweden; | |
 | | e-mail: <email address hidden> | |
 | | Torbjorn Sjostrand; Department of Astronomy and Theoretical Physics, | |
 | | Lund University, Solvegatan 14A, SE-223 62 Lund, Sweden; | |
 | | e-mail: <email address hidden> | |
 | | Peter Skands; School of Physics, | |
 | | Monash University, PO Box 27, 3800 Melbourne, Australia; | |
 | | e-mail: <email address hidden> | |
 | | | |
 | | The main program reference is 'An Introduction to PYTHIA 8.2', | |
 | | T. Sjostrand et al, Comput. Phys. Commun. 191 (2015) 159 | |
 | | [arXiv:1410.3012 [hep-ph]] | |
 | | | |
 | | The main physics reference is the 'PYTHIA 6.4 Physics and Manual', | |
 | | T. Sjostrand, S. Mrenna and P. Skands, JHEP05 (2006) 026 [hep-ph/0603175] | |
 | | | |
 | | An archive of program versions and documentation is found on the web: | |
 | | http://www.thep.lu.se/Pythia | |
 | | | |
 | | This program is released under the GNU General Public Licence version 2. | |
 | | Please respect the MCnet Guidelines for Event Generator Authors and Users. | |
 | | | |
 | | Disclaimer: this program comes without any guarantees. | |
 | | Beware of errors and use common sense when interpreting results. | |
 | | | |
 | | Copyright (C) 2019 Torbjorn Sjostrand | |
 | | | |
 | | | |
 | *------------------------------------------------------------------------------* |
 | |
 *------------------------------------------------------------------------------------*

 PYTHIA Abort from Pythia::init: Les Houches initialization failed
Counting events in input LHEF, please wait.
Found 0 events in input LHEF.

Start generating events

 *------- PYTHIA Event and Cross Section Statistics -------------------------------------------------------------*
 | |
 | Subprocess Code | Number of events | sigma +- delta |
 | | Tried Selected Accepted | (estimated) (mb) |
 | | | |
 |-----------------------------------------------------------------------------------------------------------------|
 | | | |
 | | | |
 | sum | 0 0 0 | 0.000e+00 0.000e+00 |
 | |
 *------- End PYTHIA Event and Cross Section Statistics ----------------------------------------------------------*

 *------- PYTHIA Error and Warning Messages Statistics ----------------------------------------------------------*
 | |
 | times message |
 | |
 | 2 Abort from Pythia::init: Les Houches initialization failed |
 | |
 *------- End PYTHIA Error and Warning Messages Statistics ------------------------------------------------------*

 Contribution of sample 0 to the inclusive cross section : 0.00000000e+00 +- 0.00000000e+00

Inclusive cross section: 0.00000000e+00 +- 0.00000000e+00 mb

I checked the LHE file and it is not empty. By the way I installed pythia8 separately since i encountered error in installing it within madgraph. The HEPToolInstaller is looking for "pythia82.tgz" but in the Pythia website it has only "pythia83.tgz". Any help is highly appreciated regarding the above error.

Sincerely,

Dennis

[Dennis Arogancia (dcarogancia)]

Hi,

I have attached the LHE file here.

Thanks,

Dennis

[Olivier Mattelaer (olivier-mattelaer)]

Thanks,

I do not see anything weird.
I would therefore suggest that you contact Pythia8 authors. They should be able to know what the issue is. (you can put me in cc such that I can react directly if they blame us).

Cheers,

Olivier

[Dennis Arogancia (dcarogancia)]

Hi Olivier,

I was able to fix the problem. I forgot that I have an existing pythia8 installation path in my .bashrc (my bad). What I did is perform a fresh install of pythia8 manually using the HEPToolInstaller in Madgraph after installing the dependencies (hepmc, etc) by doing this:

./HEPTools/HEPToolsInstallers/HEPToolInstaller.py pythia8 --pythia8_tarball=pythia8244.tgz

and set PYTHIA8DATA=$HOME/MG5_aMC_v2_7_2/HEPTools/pythia8/share/Pythia8/xmldoc

I also had to manually install the MG5aMC_PY8_interface.:

python compile.py pythia_installation_path

Somehow I encountered an error (cannot get the pythia version number ) using the automatic installation of MG5aMC_PY8_interface within madgraph.

Many thanks,

Dennis