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v6-22
Reference Guide
pythia8.C File Reference
Tutorials
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Detailed Description
pythia8 basic example
to run, do:
root > .x pythia8.C
#include "
TSystem.h
"
#include "
TH1F.h
"
#include "
TClonesArray.h
"
#include "
TPythia8.h
"
#include "
TParticle.h
"
#include "
TDatabasePDG.h
"
#include "
TCanvas.h
"
void
pythia8(
Int_t
nev = 100,
Int_t
ndeb = 1)
{
// Load libraries
gSystem
->
Load
(
"libEG"
);
gSystem
->
Load
(
"libEGPythia8"
);
// Histograms
TH1F
* etaH =
new
TH1F
(
"etaH"
,
"Pseudorapidity"
, 120, -12., 12.);
TH1F
* ptH =
new
TH1F
(
"ptH"
,
"pt"
, 50, 0., 10.);
// Array of particles
TClonesArray
* particles =
new
TClonesArray
(
"TParticle"
, 1000);
// Create pythia8 object
TPythia8
* pythia8 =
new
TPythia8
();
#if PYTHIA_VERSION_INTEGER == 8235
// Pythia 8.235 is known to cause crashes:
printf(
"ABORTING PYTHIA8 TUTORIAL!\n"
);
printf(
"The version of Pythia you use is known to case crashes due to memory errors.\n"
);
printf(
"They have been reported to the authors; the Pythia versions 8.1... are known to work.\n"
);
return
;
#endif
// Configure
pythia8->
ReadString
(
"HardQCD:all = on"
);
pythia8->
ReadString
(
"Random:setSeed = on"
);
// use a reproducible seed: always the same results for the tutorial.
pythia8->
ReadString
(
"Random:seed = 42"
);
// Initialize
pythia8->
Initialize
(2212
/* p */
, 2212
/* p */
, 14000.
/* TeV */
);
// Event loop
for
(
Int_t
iev = 0; iev < nev; iev++) {
pythia8->
GenerateEvent
();
if
(iev < ndeb) pythia8->
EventListing
();
pythia8->
ImportParticles
(particles,
"All"
);
Int_t
np = particles->
GetEntriesFast
();
// Particle loop
for
(
Int_t
ip = 0; ip < np; ip++) {
TParticle
* part = (
TParticle
*) particles->
At
(ip);
Int_t
ist = part->
GetStatusCode
();
// Positive codes are final particles.
if
(ist <= 0)
continue
;
Int_t
pdg = part->
GetPdgCode
();
Float_t
charge =
TDatabasePDG::Instance
()->
GetParticle
(pdg)->
Charge
();
if
(charge == 0.)
continue
;
Float_t
eta = part->
Eta
();
Float_t
pt
= part->
Pt
();
etaH->
Fill
(eta);
if
(
pt
> 0.) ptH->
Fill
(
pt
, 1./(2. *
pt
));
}
}
pythia8->
PrintStatistics
();
TCanvas
*
c1
=
new
TCanvas
(
"c1"
,
"Pythia8 test example"
,800,800);
c1
->Divide(1, 2);
c1
->cd(1);
etaH->
Scale
(5./
Float_t
(nev));
etaH->
Draw
();
etaH->
SetXTitle
(
"#eta"
);
etaH->
SetYTitle
(
"dN/d#eta"
);
c1
->cd(2);
gPad
->SetLogy();
ptH->
Scale
(5./
Float_t
(nev));
ptH->
Draw
();
ptH->
SetXTitle
(
"p_{t} [GeV/c]"
);
ptH->
SetYTitle
(
"dN/dp_{t}^{2} [GeV/c]^{-2}"
);
}
Int_t
int Int_t
Definition:
RtypesCore.h:43
Float_t
float Float_t
Definition:
RtypesCore.h:55
TCanvas.h
TClonesArray.h
TDatabasePDG.h
TH1F.h
TParticle.h
TPythia8.h
TSystem.h
gSystem
R__EXTERN TSystem * gSystem
Definition:
TSystem.h:556
gPad
#define gPad
Definition:
TVirtualPad.h:287
TCanvas
The Canvas class.
Definition:
TCanvas.h:27
TClonesArray
An array of clone (identical) objects.
Definition:
TClonesArray.h:32
TDatabasePDG::Instance
static TDatabasePDG * Instance()
static function
Definition:
TDatabasePDG.cxx:106
TDatabasePDG::GetParticle
TParticlePDG * GetParticle(Int_t pdgCode) const
Get a pointer to the particle object according to the MC code number.
Definition:
TDatabasePDG.cxx:232
TH1F
1-D histogram with a float per channel (see TH1 documentation)}
Definition:
TH1.h:571
TH1::SetXTitle
virtual void SetXTitle(const char *title)
Definition:
TH1.h:409
TH1::Fill
virtual Int_t Fill(Double_t x)
Increment bin with abscissa X by 1.
Definition:
TH1.cxx:3275
TH1::Draw
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition:
TH1.cxx:2998
TH1::SetYTitle
virtual void SetYTitle(const char *title)
Definition:
TH1.h:410
TH1::Scale
virtual void Scale(Double_t c1=1, Option_t *option="")
Multiply this histogram by a constant c1.
Definition:
TH1.cxx:6246
TObjArray::GetEntriesFast
Int_t GetEntriesFast() const
Definition:
TObjArray.h:64
TObjArray::At
TObject * At(Int_t idx) const
Definition:
TObjArray.h:166
TParticlePDG::Charge
Double_t Charge() const
Definition:
TParticlePDG.h:68
TParticle
Description of the dynamic properties of a particle.
Definition:
TParticle.h:26
TParticle::GetStatusCode
Int_t GetStatusCode() const
Definition:
TParticle.h:82
TParticle::GetPdgCode
Int_t GetPdgCode() const
Definition:
TParticle.h:83
TParticle::Pt
Double_t Pt() const
Definition:
TParticle.h:135
TParticle::Eta
Double_t Eta() const
Definition:
TParticle.h:137
TPythia8
TPythia8 is an interface class to C++ version of Pythia 8.1 event generators, written by T....
Definition:
TPythia8.h:77
TPythia8::ReadString
void ReadString(const char *string) const
Configuration.
Definition:
TPythia8.cxx:300
TPythia8::Initialize
Bool_t Initialize(Int_t idAin, Int_t idBin, Double_t ecms)
Initialization.
Definition:
TPythia8.cxx:147
TPythia8::EventListing
void EventListing() const
Event listing.
Definition:
TPythia8.cxx:364
TPythia8::PrintStatistics
void PrintStatistics() const
Print end of run statistics.
Definition:
TPythia8.cxx:356
TPythia8::GenerateEvent
virtual void GenerateEvent()
Generate the next event.
Definition:
TPythia8.cxx:185
TPythia8::ImportParticles
virtual Int_t ImportParticles(TClonesArray *particles, Option_t *option="")
Import particles from Pythia stack.
Definition:
TPythia8.cxx:194
TSystem::Load
virtual int Load(const char *module, const char *entry="", Bool_t system=kFALSE)
Load a shared library.
Definition:
TSystem.cxx:1850
pt
TPaveText * pt
Definition:
entrylist_figure1.C:7
c1
return c1
Definition:
legend1.C:41
Author
Andreas Morsch
Definition in file
pythia8.C
.
tutorials
pythia
pythia8.C
ROOT v6-22 - Reference Guide Generated on Fri Apr 1 2022 11:54:20 (GVA Time) using Doxygen 1.9.4