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| − | == Histogramming b<sub>1</sub>(1235)<sup>+</sup> Invariant Mass in b1pi ==
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| − | * Assumes the DReaction has been setup as shown in: [[Analysis_DReaction | DReaction]]
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| − | === Minimal/Simplest ===
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| − | * Minimal: No check against double-counting, using kinematic fit data only.
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| − | ** Not best practice: intended only as a simple illustration.
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| − | * In your DEventProcessor class definition (header):
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| − | <syntaxhighlight>
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| − | TH1D* dHist_omegaMass;
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| − | </syntaxhighlight>
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| − |
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| − | * In your DEventProcessor init() method:
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| − | <syntaxhighlight>
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| − | dHist_omegaMass = new TH1D("B1InvariantMass", ";#pi^{+}#omega Invariant Mass (GeV/c^{2})", 600, 0.6, 1.8);
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| − | </syntaxhighlight>
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| − |
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| − | * In your DEventProcessor evnt() method:
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| − | <syntaxhighlight>
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| − | vector<const DParticleCombo*> locParticleCombos;
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| − | locEventLoop->Get(locParticleCombos);
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| − |
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| − | for(size_t loc_i = 0; loc_i < locParticleCombos.size(); ++loc_i)
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| − | {
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| − | if(locParticleCombos[loc_i]->Get_Reaction()->Get_ReactionName() != "b1pi")
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| − | continue; //wrong DReaction
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| − |
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| − | // get omega combo step //0 is photoproduction, 1 is omega decay, 2 is pi0 decay
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| − | const DParticleComboStep* locParticleComboStep0 = locParticleCombo->Get_ParticleComboStep(0);
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| − | const DParticleComboStep* locParticleComboStep1 = locParticleCombo->Get_ParticleComboStep(1);
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| − | // calculate b1+ p4 with kinematic fit data
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| − | TLorentzVector locP4;
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| − | locP4 += locParticleComboStep0->Get_FinalParticle(2)->lorentzMomentum(); //pi+
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| − | locP4 += locParticleComboStep1->Get_FinalParticle(0)->lorentzMomentum(); //pi+
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| − | locP4 += locParticleComboStep1->Get_FinalParticle(1)->lorentzMomentum(); //pi-
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| − | locP4 += locParticleComboStep1->Get_FinalParticle(2)->lorentzMomentum(); //pi0
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| − |
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| − | Get_Application()->RootWriteLock(); //ACQUIRE ROOT LOCK!!
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| − | {
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| − | dHist_omegaMass->Fill(locP4.M());
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| − | }
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| − | Get_Application()->RootUnLock(); //RELEASE ROOT LOCK!!
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| − | break;
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| − | }
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| − | </syntaxhighlight>
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| − |
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| − | === Thorough: Using an Analysis Action ===
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| − | * Checks against double-counting, shows/allows histogramming measured or kinfit data.
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| − | * See DCustomAction_HistMass_b1_1235 in the [https://halldsvn.jlab.org/repos/trunk/sim-recon/src/programs/Analysis/plugins/b1pi_hists/ b1pi Plugin]
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| − |
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| − | * Add to your DReaction anywhere in the analysis chain:
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| − | <syntaxhighlight>
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| − | locReaction->Add_AnalysisAction(new DCustomAction_HistMass_b1_1235(locReaction, false)); //false: measured data
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| − | locReaction->Add_AnalysisAction(new DCustomAction_HistMass_b1_1235(locReaction, true, "KinFit")); //true: kinfit data //"KinFit:" a unique, distinguishing string (could have been anything)
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| − | </syntaxhighlight>
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| − |
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| − | == Kinematic Fit Confidence Level ==
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| − | * In your DEventProcessor evnt() method:
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| − |
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| − | <syntaxhighlight>
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| − | vector<const DParticleCombo*> locParticleCombos;
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| − | locEventLoop->Get(locParticleCombos);
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| − |
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| − | for(size_t loc_i = 0; loc_i < locParticleCombos.size(); ++loc_i)
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| − | {
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| − | if(locParticleCombos[loc_i]->Get_Reaction()->Get_ReactionName() != "b1pi")
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| − | continue; //wrong DReaction
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| − | const DKinFitResults* locKinFitResults = locParticleCombos[loc_i]->Get_KinFitResults();
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| − | double locConfidenceLevel = locKinFitResults->Get_ConfidenceLevel();
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| − | }
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| − | </syntaxhighlight>
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| − |
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| − | == Getting the Thrown Track Topology ==
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| − |
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| − | * There are several ways of getting the thrown track information. The most direct way of getting it is to ask JANA for the <span style="color:#0000FF">DMCThrown</span> particles (see below). The <span style="color:#0000FF">DMCThrown</span>::<span style="color:#008000">parentid</span> member variable matches the <span style="color:#0000FF">DMCThrown</span>::<span style="color:#008000">myid</span> member variable that the particle decayed from. If it did not decay from any particle (e.g. was directly photoproduced by the generator) then the <span style="color:#0000FF">DMCThrown</span>::<span style="color:#008000">parentid</span> member will equal 0.
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| − |
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| − | <syntaxhighlight>
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| − | vector<const DMCThrown*> locMCThrowns;
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| − | locEventLoop->Get(locMCThrowns);
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| − | </syntaxhighlight>
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| − |
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| − | * Note that you can use the <span style="color:Red">"Primary,"</span> <span style="color:Red">"Decaying,"</span> and <span style="color:Red">"FinalState"</span> tags for the <span style="color:#0000FF">DMCThrown</span> factory to get specific types of thrown particles.
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| − |
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| − | * An easier way of getting the information is by asking JANA for the thrown <span style="color:#0000FF">DReaction</span> and <span style="color:#0000FF">DParticleCombo</span> objects. These are accessible by requesting these objects with the "Thrown" tag (see below). These contain the PIDs (<span style="color:#0000FF">DReaction</span>) and track kinematics (<span style="color:#0000FF">DParticleCombo</span>) of the thrown particles, organized by the event's decay chain.
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| − | **'''NOTE''': when producing these, any decays of kaons, pions, muons, and neutrons are ignored.
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| − | **'''NOTE''': if a particle type is not defined in sim-recon/src/libraries/include/particleType.h, then it is ignored when generating these objects.
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| − |
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| − | <syntaxhighlight>
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| − | vector<const DReaction*> locThrownReactions;
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| − | locEventLoop->Get(locThrownReactions, "Thrown");
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| − | const DReaction* locThrownReaction = locThrownReactions[0];
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| − | deque<Particle_t> locThrownPIDs;
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| − | locThrownReaction->Get_DetectedFinalPIDs(locThrownPIDs, true); //true tells it to include duplicates (so if two pi-'s, list it twice).
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| − |
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| − | vector<const DParticleCombo*> locThrownParticleCombos;
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| − | locEventLoop->Get(locThrownParticleCombos, "Thrown");
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| − | const DParticleCombo* locThrownParticleCombo = locThrownParticleCombos[0];
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| − | </syntaxhighlight>
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