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Reference Guide
pythia8.C File Reference

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
// 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();
// Pythia 8.235 is known to cause crashes:
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");
// 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++) {
if (iev < ndeb) pythia8->EventListing();
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();
if (charge == 0.) continue;
Float_t eta = part->Eta();
Float_t pt = part->Pt();
if (pt > 0.) ptH->Fill(pt, 1./(2. * pt));
TCanvas* c1 = new TCanvas("c1","Pythia8 test example",800,800);
c1->Divide(1, 2);
ptH->SetXTitle("p_{t} [GeV/c]");
ptH->SetYTitle("dN/dp_{t}^{2} [GeV/c]^{-2}");
int Int_t
Definition: RtypesCore.h:45
float Float_t
Definition: RtypesCore.h:57
Option_t Option_t TPoint TPoint const char GetTextMagnitude GetFillStyle GetLineColor GetLineWidth GetMarkerStyle GetTextAlign GetTextColor GetTextSize void char Point_t Rectangle_t WindowAttributes_t Float_t Float_t Float_t Int_t Int_t UInt_t UInt_t Rectangle_t Int_t Int_t Window_t TString Int_t GCValues_t GetPrimarySelectionOwner GetDisplay GetScreen GetColormap GetNativeEvent const char const char dpyName wid window const char font_name cursor keysym reg const char only_if_exist regb h Point_t np
R__EXTERN TSystem * gSystem
Definition: TSystem.h:559
#define gPad
Definition: TVirtualPad.h:288
The Canvas class.
Definition: TCanvas.h:23
An array of clone (identical) objects.
Definition: TClonesArray.h:29
static TDatabasePDG * Instance()
static function
TParticlePDG * GetParticle(Int_t pdgCode) const
Get a pointer to the particle object according to the MC code number.
1-D histogram with a float per channel (see TH1 documentation)}
Definition: TH1.h:574
virtual void SetXTitle(const char *title)
Definition: TH1.h:412
virtual Int_t Fill(Double_t x)
Increment bin with abscissa X by 1.
Definition: TH1.cxx:3348
void Draw(Option_t *option="") override
Draw this histogram with options.
Definition: TH1.cxx:3070
virtual void SetYTitle(const char *title)
Definition: TH1.h:413
virtual void Scale(Double_t c1=1, Option_t *option="")
Multiply this histogram by a constant c1.
Definition: TH1.cxx:6594
Int_t GetEntriesFast() const
Definition: TObjArray.h:58
TObject * At(Int_t idx) const override
Definition: TObjArray.h:164
Double_t Charge() const
Definition: TParticlePDG.h:68
Description of the dynamic properties of a particle.
Definition: TParticle.h:26
Int_t GetStatusCode() const
Definition: TParticle.h:82
Int_t GetPdgCode() const
Definition: TParticle.h:83
Double_t Pt() const
Definition: TParticle.h:135
Double_t Eta() const
Definition: TParticle.h:137
TPythia8 is an interface class to C++ version of Pythia 8.1 event generators, written by T....
Definition: TPythia8.h:77
void ReadString(const char *string) const
Definition: TPythia8.cxx:300
Bool_t Initialize(Int_t idAin, Int_t idBin, Double_t ecms)
Definition: TPythia8.cxx:147
void EventListing() const
Event listing.
Definition: TPythia8.cxx:364
void PrintStatistics() const
Print end of run statistics.
Definition: TPythia8.cxx:356
virtual void GenerateEvent()
Generate the next event.
Definition: TPythia8.cxx:185
virtual Int_t ImportParticles(TClonesArray *particles, Option_t *option="")
Import particles from Pythia stack.
Definition: TPythia8.cxx:194
virtual int Load(const char *module, const char *entry="", Bool_t system=kFALSE)
Load a shared library.
Definition: TSystem.cxx:1855
TPaveText * pt
return c1
Definition: legend1.C:41
Andreas Morsch

Definition in file pythia8.C.