Hi!
I am trying to make tree.cc example work in Pythia8. [code]// File: tree.cc
// This is a simple test program.
// Modified by Rene Brun and Axcel Naumann to put the Pythia::event
// into a TTree.
// Copyright © 2014 Torbjorn Sjostrand
// Header file to access Pythia 8 program elements.
#include
#include “Pythia8/Pythia.h”
//#include “Pythia8/Pythia.h”
// ROOT, for saving Pythia events as trees in a file.
#include “TTree.h”
#include “TFile.h”
using namespace Pythia8;
int main() {
// Create Pythia instance and set it up to generate hard QCD processes
// above pTHat = 20 GeV for pp collisions at 14 TeV.
Pythia pythia;
pythia.readString(“HardQCD:all = on”);
pythia.readString(“PhaseSpace:pTHatMin = 20.”);
pythia.readString(“Beams:eCM = 14000.”);
// pythia.init();
pythia.init();
// Set up the ROOT TFile and TTree.
TFile *file = TFile::Open(“pytree.root”,“recreate”);
Event *event = &pythia.event;
TTree *T = new TTree(“T”,“event”);
T->Branch(“event”,&event);
// Begin event loop. Generate event; skip if generation aborted.
for (int iEvent = 0; iEvent < 10; ++iEvent) {
if (!pythia.next()) continue;
// Fill the pythia event into the TTree.
// Warning: the files will rapidly become large if all events
// are saved. In some cases it may be convenient to do some
// processing of events and only save those that appear
// interesting for future analyses.
T->Fill();
// End event loop.
}
// Statistics on event generation.
pythia.stat();
// Write tree.
T->Print();
T->Write();
delete file;
// Done.
return 0;
}
[/code]
On running the tree.exe file, I get the following error:
and the TTree contains the following
[code]************
- Row *
-
0 * -
1 * -
2 * -
3 * -
4 * -
5 * -
6 * -
7 * -
8 * -
9 *
[/code]
That is, I guess no events were stored. I tried solving the problem by re-building ROOT with ./configure --enable-pythia8. The version of ROOT that I am using now is 5.34/24, and it gives the exact same error (before rebuilding I was using 5.34/18).
Can someone please help me with this?
Thanks in advance,
Aman