Getting charge of a particle from TDatabasePDG fails for (PID=42)

Newbie
1

ROOT Version: 6.30/02
Platform: Ubuntu 22.04.3 LTS
Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0

Hi,

I have a macro where I want to get the charge of a particle from its pid. But my macro is giving the following error

In file included from input_line_8:1:
myCODE/CheckRootFile.C:70:19: warning: null passed to a callee that requires a non-null argument [-Wnonnull]
          charge  = TDatabasePDG::Instance()->GetParticle(Pid)->Charge();

I checked my data files…It’s happening for Pid=42;

Regards

2

Welcome to the ROOT forum.

The line on wish you get the error looks correct.
Do you have a small code snippet reproducing the problem?

3 
void CheckRootFile::Loop()
{
//   In a ROOT session, you can do:
//      root> .L CheckRootFile.C
//      
   if (fChain == 0) return;

   Long64_t nentries = fChain->GetEntriesFast();
   
   cout << nentries   << endl;  

   Long64_t nbytes = 0, nb = 0;
   
   //Event Loop
   
   for (Long64_t jentry=0; jentry<nentries;jentry++) {
      Long64_t ientry = LoadTree(jentry);
      if (ientry < 0) break;
      nb = fChain->GetEntry(jentry);   nbytes += nb;
      
      cout << jentry << endl;
      
      
       //Particle Loop
      for (int p1=0; p1<fNpa;p1++)
	
	
	{
	
	Int_t     Pid= fParticles_fPdg[p1];
	
	Double32_t   Px= fParticles_fPx[p1]; 
	Double32_t   Py= fParticles_fPy[p1]; 
	Double32_t   Pz= fParticles_fPz[p1]; 
	Double32_t   E= fParticles_fE[p1]; 
	 
	//  cout << jentry<<">>>>"<<Px  << ":::::"<<Py<< ":::::" << Pz << ":::::" << E << endl;
	 
	  
	  Int_t charge=0;
	  Double_t mass=0;
     	  
     	  charge  = TDatabasePDG::Instance()->GetParticle(Pid)->Charge();
     	  mass  = TDatabasePDG::Instance()->GetParticle(Pid)->Mass();
          cout << p1 <<"::::"<<Pid<<">>>>"<< "charge" << ":::::"<<mass<<endl;
      
	}
	
	//particle loop ends
      // if (Cut(ientry) < 0) continue;
   }//Event Loop ends
}//Main LOOP()
4

This code cannot be run.

May be you can try this on (it prints Pid):

void CheckRootFile::Loop()
{
//   In a ROOT session, you can do:
//      root> .L CheckRootFile.C
//
   if (fChain == 0) return;
   Long64_t nentries = fChain->GetEntriesFast();
   cout << nentries   << endl;
   Long64_t nbytes = 0, nb = 0;

   //Event Loop
   for (Long64_t jentry=0; jentry<nentries;jentry++) {
      Long64_t ientry = LoadTree(jentry);
      if (ientry < 0) break;
      nb = fChain->GetEntry(jentry);   nbytes += nb;
      cout << jentry << endl;
      //Particle Loop
      for (int p1=0; p1<fNpa;p1++) {
         Int_t Pid = fParticles_fPdg[p1];
         Double32_t Px = fParticles_fPx[p1];
         Double32_t Py = fParticles_fPy[p1];
         Double32_t Pz = fParticles_fPz[p1];
         Double32_t E = fParticles_fE[p1];
         Int_t charge = 0;
         Double_t mass = 0;
         cout << "Pid = " << Pid << endl;
         charge  = TDatabasePDG::Instance()->GetParticle(Pid)->Charge();
         mass  = TDatabasePDG::Instance()->GetParticle(Pid)->Mass();
         cout << p1 <<"::::"<<Pid<<">>>>"<< "charge" << ":::::"<<mass<<endl;
      }
   }
}

And copy/paste here the output you get.

5 
470::::3112>>>>charge:::::1.19745
Pid = -211
471::::-211>>>>charge:::::0.13957
Pid = 2112
472::::2112>>>>charge:::::0.939565
Pid = -211
473::::-211>>>>charge:::::0.13957
Pid = 111
474::::111>>>>charge:::::0.134977
Pid = 2212
475::::2212>>>>charge:::::0.938272
Pid = 321
476::::321>>>>charge:::::0.493677
Pid = 42
Error in <HandleInterpreterException>: Trying to dereference null pointer or trying to call routine taking non-null arguments
Execution of your code was aborted.
In file included from input_line_8:1:
/home/arshad/WorkSpace/LEARN/Centrality/myCODE/CheckRootFile.C:36:20: warning: null passed to a callee that requires a non-null argument [-Wnonnull]
         charge  = TDatabasePDG::Instance()->GetParticle(Pid)->Charge();
6

Well, it looks like TDatabasePDG has no entry for ID 42:

root [0] TDatabasePDG::Instance()->GetParticle(42)
(TParticlePDG *) nullptr
root [1]

Sor you should do something like:

   auto particlePDG = TDatabasePDG::Instance()->GetParticle(Pid);
   if (particlePDG)
      charge = particlePDG->Charge();
   ...
7

Yes, Its Working Now
Thanks a lot!!!

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