Unable to run Pythia8 using ROOT 6 (unable to find TPythia8.h file)

[Zman]

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ROOT Version: rootv6.12.06
Platform: Ubuntu 16.04

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My primary motive is to run Pythia8 directly using ROOT6.12.06. In better word, I want to run a pythia8 code and plot the data, all using a single macro and running it in ROOT.

So, what I did is mentioned step by step:

I installed ROOT 6.12.06 successfully in the location:

/usr/local/root

and added the following lines at the end of the .bashrc file, as mentioned in the ROOT readme file:

export ROOTSYS=/usr/local/root
export PATH=$ROOTSYS/bin:$PATH
export PYTHONDIR=$ROOTSYS
export LD_LIBRARY_PATH=$ROOTSYS/lib:$ROOTSYS/bindings/pyroot:$LD_LIBRARY_PATH
export PYTHONPATH=$ROOTSYS/lib:$PYTHONPATH:$ROOTSYS/bindings/pyroot

After that, I could open ROOT from any directory successfully and execute simple ROOT macros without any error.

Then, I installed Pythia 8.186 successfully, following instructions mentioned in the Lund University webpage, in the location:

/home/hp/Pythia8Progs/pythia8186

and as per this link, I further added these lines to my .bashrc file:

source /usr/local/root/bin/thisroot.sh
export PYTHIA8=/home/hp/Pythia8Progs/pythia8186
export LD_LIBRARY_PATH=$PYTHIA/lib:$LD_LIBRARY_PATH

Then I ran the pythia8.C file stored in the tutorials subdirectory of ROOT and this is the error that it showed:

root [6] .x pythia8.C
In file included from input_line_101:1:
/usr/local/root/tutorials/pythia/pythia8.C:23:10: fatal error: 'TPythia8.h' file not found
#include "TPythia8.h"
         ^~~~~~~~~~~~
/usr/local/root/tutorials/pythia/pythia8.C:41:4: error: unknown type name 'TPythia8'
   TPythia8* pythia8 = new TPythia8();
   ^
/usr/local/root/tutorials/pythia/pythia8.C:41:28: error: unknown type name 'TPythia8'
   TPythia8* pythia8 = new TPythia8();

I have done exactly what I have stated above. I don’t know what is wrong with the file and why it is not running. I presume somehow ROOT cannot find the TPythia8.h file stored in:
/usr/local/root/montecarlo/pythia8/TPythia8.h

But I don’t know how to correct it.

Please help. And suggest me if I can do anything else in order to run Pythia8 from ROOT6 itself.

[oshadura]

Hi, I think you opened other post How to configure ROOT after installation
about Pythia8 configuration. Did you build ROOT with -Dpythia8=ON enabled and do you know if Pythia8 library was detected by ROOT during configuration step?

[Zman]

No I did not do that step and hence I opened the other post to know if I could configure it now.
I dont know if the Pythia8 library was detected by ROOT during configuration step but there is no libEGPythia8 in the ROOT directory, that is perhaps very much needed for this.