// EVENT DATA
"RunNumber": UInt_t
"EventNumber": ULong64_t
"MCWeight": Float_t
 
// # PARTICLES //array size of the thrown particle branches
"NumThrown": UInt_t
 
// THROWN REACTION INFO
"NumPIDThrown_FinalState": ULong64_t //the # of thrown final-state particles (+ pi0) of each type (multiplexed in base 10)
                                       //types (in order from 10^0 -> 10^15): g, e+, e-, nu, mu+, mu-, pi0, pi+, pi-, KLong, K+, K-, n, p, p-bar, n-bar
                                       //e.g. particles decaying from final-state particles are NOT included (e.g. photons from pi0, muons from pions, etc.)
                                     //is sum of #-of-PID * 10^ParticleMultiplexPower() (defined in libraries/include/particleType.h)
                                     //ParticleMultiplexPower() returns a different power of 10 for each final-state PID type. 
                                     //A value of 9 should be interpreted as >= 9.  
"PIDThrown_Decaying": ULong64_t //the types of the thrown decaying particles in the event (multiplexed in base 2)
                                //not the quantity of each, just whether or not they were present (1 or 0)
                                //binary power of a PID is given by ParticleMultiplexPower() (defined in libraries/include/particleType.h)
                                //types: most Particle_t's that aren't final state (e.g. lambda, eta, phi, rho0, etc.) see ParticleMultiplexPower()

//IDENTIFIER
"PID": Int_t //PDG ID value
 
//KINEMATICS: //At the production vertex 
"X4": TLorentzVector //This is the TAGGED energy //Use THIS for binning your results //Is ZERO if NOT TAGGED
"P4": TLorentzVector
"GeneratedEnergy": Float_t

//IDENTIFIERS / MATCHING
"ParentIndex": Int_t["NumThrown"] //the thrown particle array index of the particle this particle decayed from (-1 if none (e.g. photoproduced))
"PID": Int_t["NumThrown"] //PDG ID value
 
//MATCHING //only present if reconstructed data present (i.e. not if thrown-only tree)
"MatchID": Int_t["NumThrown"] //the "NeutralID"/"TrackID" of the reconstructed neutral/track that it is matched with (-1 for no match)
"MatchFOM": Float_t["NumThrown"] //Neutrals: confidence level //Tracks: #-matched-hits * hit_fraction //(-1 for no match)
 
//KINEMATICS: //Reported at the particle's production vertex 
"X4": TClonesArray(TLorentzVector["NumThrown"])
"P4": TClonesArray(TLorentzVector["NumThrown"])

// EVENT DATA
"RunNumber": UInt_t
"EventNumber": ULong64_t
"L1TriggerBits": UInt_t
 
// PRODUCTION SPACETIME
"X4_Production": TLorentzVector //V3 from DVertex (kinfit), t from RF (propagated to V3)
 
// # PARTICLES //these are the array sizes for the particle branches
"NumBeam": UInt_t
"NumChargedHypos": UInt_t
"NumNeutralHypos": UInt_t
 
// TOPOLOGY //only present if simulated data
"IsThrownTopology": Bool_t //Does the DReaction decay chain match the thrown decay chain
 
// UNUSED TRACKS
"NumUnusedTracks": UChar_t
 
//NUM COMBOS
"NumCombos": UInt_t //size of all of the particle-combo-content arrays

//ONLY PRESENT IF BEAM USED IN PARTICLE COMBOS
 
//IDENTIFIERS / MATCHING
"PID": Int_t["NumBeam"] //PDG ID value
"IsGenerator": Bool_t["NumBeam"] // kTRUE/kFALSE if matches the generator beam photon (-1 for no match) //only present if simulated data
 
//KINEMATICS: MEASURED //At the production vertex
"X4_Measured": TClonesArray(TLorentzVector["NumBeam"]) //position is at the production vertex (same as X4_Production(), except the time)
"P4_Measured": TClonesArray(TLorentzVector["NumBeam"])

//IDENTIFIERS / MATCHING
"TrackID": Int_t["NumChargedHypos"] //each physical particle has its own # (to keep track of different pid hypotheses for the same particle)
"PID": Int_t["NumChargedHypos"] //PDG ID value
"ThrownIndex": Int_t["NumChargedHypos"] //the array index of the thrown particle it is matched with (-1 for no match) //only present if simulated data
 
//KINEMATICS: MEASURED  //At the production vertex 
"P4_Measured": TClonesArray(TLorentzVector["NumChargedHypos"])
"X4_Measured": TClonesArray(TLorentzVector["NumChargedHypos"]) //t is the measured value in TOF/BCAL/FCAL projected back to Position_Measured
 
//TRACKING INFO:
"NDF_Tracking": UInt_t["NumChargedHypos"]
"ChiSq_Tracking": Float_t["NumChargedHypos"]
"NDF_DCdEdx": UInt_t["NumChargedHypos"]
"ChiSq_DCdEdx": Float_t["NumChargedHypos"]
"dEdx_CDC": Float_t["NumChargedHypos"]
"dEdx_FDC": Float_t["NumChargedHypos"]
 
//TIMING INFO
"HitTime": Float_t["NumChargedHypos"] //the system that is hit is in order of preference: BCAL/TOF/FCAL/ST 
                                      //to determine which, look whether energy was deposited in these systems
"RFDeltaTVar": Float_t["NumChargedHypos"] //Variance of X4_Measured.T() - RFTime, regardless of which RF bunch is chosen. 
                                          //Can be used to compute timing ChiSq //RF bunch is combo-dependent
 
//PID INFO
"Beta_Timing": Float_t["NumChargedHypos"] // = Path_Length/(c*Delta_t)
"ChiSq_Timing": Float_t["NumChargedHypos"]
"NDF_Timing": UInt_t["NumChargedHypos"]
 
//HIT ENERGY:
"dEdx_TOF": Float_t["NumChargedHypos"]
"dEdx_ST": Float_t["NumChargedHypos"]
"Energy_BCAL": Float_t["NumChargedHypos"]
"Energy_BCALPreshower": Float_t["NumChargedHypos"]
"Energy_FCAL": Float_t["NumChargedHypos"]
 
//SHOWER WIDTH:
"SigLong_BCAL" Float_t["NumChargedHypos"] // Longitudinal (outward radially from the target) shower width
"SigTheta_BCAL" Float_t["NumChargedHypos"] // Theta shower width
"SigTrans_BCAL" Float_t["NumChargedHypos"] // Transverse (azimuthal) shower width 
 
//SHOWER MATCHING:
"TrackBCAL_DeltaPhi": Float_t["NumChargedHypos"] //999.0 if not matched //units are radians
"TrackBCAL_DeltaZ": Float_t["NumChargedHypos"] //999.0 if not matched //Track position - BCAL Shower
"TrackFCAL_DOCA": Float_t["NumChargedHypos"] //999.0 if not matched

//IDENTIFIERS / MATCHING
"NeutralID": Int_t["NumNeutralHypos"] //each physical particle has its own # (to keep track of different pid hypotheses for the same particle)
"PID": Int_t["NumNeutralHypos"] //PDG ID value
"ThrownIndex": Int_t["NumNeutralHypos"] //the array index of the thrown particle it is matched with (-1 for no match) //only present if simulated data
 
//KINEMATICS: MEASURED  //At the production vertex 
"P4_Measured": TClonesArray(TLorentzVector["NumNeutralHypos"])
"X4_Measured": TClonesArray(TLorentzVector["NumNeutralHypos"]) //t is the measured value in TOF/BCAL/FCAL projected back to Position_Measured
 
//MEASURED PID INFO
"Beta_Timing": Float_t["NumNeutralHypos"] // = Path_Length/(c*Delta_t)
"ChiSq_Timing": Float_t["NumNeutralHypos"] //-1 if not photon
"NDF_Timing": UInt_t["NumNeutralHypos"] //0 if not photon
 
//SHOWER INFO
"X4_Shower": Float_t["NumNeutralHypos"] //location/time of the reconstructed shower
"Energy_BCAL": Float_t["NumNeutralHypos"] //is 0.0 if shower in FCAL
"Energy_BCALPreshower": Float_t["NumNeutralHypos"] //is 0.0 if shower in FCAL
"Energy_FCAL": Float_t["NumNeutralHypos"] //is 0.0 if shower in BCAL
 
//SHOWER WIDTH:
"SigLong_BCAL" Float_t["NumNeutralHypos"] // Longitudinal (outward radially from the target) shower width
"SigTheta_BCAL" Float_t["NumNeutralHypos"] // Theta shower width
"SigTrans_BCAL" Float_t["NumNeutralHypos"] // Transverse (azimuthal) shower width 
 
//NEARBY TRACKS
"TrackBCAL_DeltaPhi": Float_t["NumNeutralHypos"] //is delta to nearest track, is 999.0 if no tracks on BCAL
"TrackBCAL_DeltaZ": Float_t["NumNeutralHypos"] //is delta to nearest track, is 999.0 if no tracks on BCAL
"TrackFCAL_DOCA": Float_t["NumNeutralHypos"] //is DOCA to nearest track, is 999.0 if no tracks on FCAL
 
//PHOTON PID INFO
   //Computed using DVertex (best estimate of reaction vertex using all "good" tracks)
   //Can be used to compute timing chisq //is invalid (0) for non-photons
"PhotonRFDeltaTVar": Float_t["NumNeutralHypos"] //Variance of DVertexX4.T() - RFTime, regardless of which RF bunch is chosen. //RF bunch is combo-dependent

//CUT FLAG
"IsComboCut": Bool_t["NumCombos"] //if true, combo has been previously cut (all kFALSE originally, user can apply cuts in TSelector, change this flag, and output new TTree)
 
//COMBO THROWN MATCHING //not present if not simulated data
"IsTrueCombo": Bool_t["NumCombos"] //"IsThrownTopology" = kTRUE, each particle has the right PID, and the combo particle chain matches the thrown decay chain
"IsBDTSignalCombo": Bool_t["NumCombos"] //Similar to "IsTrueCombo", except other thrown topologies that decay to the DReaction topology are marked as signal
                                        //Note that if you have an ω or φ in your DReaction, you still have to filter your combos prior to BDT 
                                        //input to remove duplicate entries. This is because the omega & phi masses are not constrained in the kinematic fit, 
                                        //nor should they be in the BDT, so you have duplicate entries from the point-of-view of the BDT due to combinatorics 
                                        //(e.g. which pions decayed from the omega, and which ones didn't, are irrelevant to the BDT). 
 
//RF
"RFTime_Measured": Float_t["NumCombos"] //reported at center of target
"RFTime_KinFit": Float_t["NumCombos"] //reported at center of target //only if spacetime kinematic fit performed
 
//KINEMATIC FIT
"ChiSq_KinFit": Float_t["NumCombos"] //only if kinematic fit performed
"NDF_KinFit": UInt_t["NumCombos"] //only if kinematic fit performed // = 0 if kinematic fit doesn't converge
 
//UNUSED ENERGY
"Energy_UnusedShowers": Float_t["NumCombos"] // summed energy of neutral showers in the event not included in the combo (requiring unused showers are in time and have a polar angle > 2 degrees to reduce contamination from EM background)
 
//UNUSED TRACKS //For tracks unused by combo, the hypo chosen is the one with the best tracking FOM
"SumPMag_UnusedTracks": Float_t["NumCombos"]
"SumP3_UnusedTracks": TClonesArray(TVector3["NumCombos"])

//IDENTIFIER
"BeamIndex": Int_t["NumCombos"] //array index to the "Beam__" branches that correspond to this particle
 
//KINEMATICS: KINFIT //At the interaction vertex //only present if kinfit performed
"X4_KinFit": TClonesArray(TLorentzVector["NumCombos"]) //not present if p4-only fit
"P4_KinFit": TClonesArray(TLorentzVector["NumCombos"]) //not present if vertex-only or spacetime-only fit, unless beam is charged

//IDENTIFIER
"ChargedIndex": Int_t["NumCombos"] //array index to the "ChargedHypo__" branches that correspond to this particle
 
//PID INFO: MEASURED //using combo RF bunch
"Beta_Timing_Measured": Float_t["NumCombos"] // = Path_Length/(c*Delta_t)
"ChiSq_Timing_Measured": Float_t["NumCombos"]
 
//PID INFO: KINFIT //using combo RF bunch //not present if time constrained //uses combo vertex & p4 if kinfit
"Beta_Timing_KinFit": Float_t["NumCombos"] // = Path_Length/(c*Delta_t)
"ChiSq_Timing_KinFit": Float_t["NumCombos"]
 
//KINEMATIC FIT KINEMATICS //only present if kinfit performed
"X4_KinFit": TClonesArray(TLorentzVector["NumCombos"]) //not present if p4-only fit
"P4_KinFit": TClonesArray(TLorentzVector["NumCombos"])

//IDENTIFIER
"NeutralIndex": Int_t["NumCombos"] //array index to the "NeutralHypo__" branches that correspond to this particle
                                   //Note that they may not have the same PID (and thus P4) as this!!
                                      //If this is a PID not created by default (e.g. K0Long)
 
//KINEMATICS: MEASURED  //At the production vertex 
"P4_Measured": TClonesArray(TLorentzVector["NumCombos"])
"X4_Measured": TClonesArray(TLorentzVector["NumCombos"]) //t is the measured value in TOF/BCAL/FCAL projected back to Position_Measured
 
//MEASURED PID INFO
"Beta_Timing_Measured": Float_t["NumCombos"] // = Path_Length/(c*Delta_t)
"ChiSq_Timing_Measured": Float_t["NumCombos"] //only present if photon
 
//KINEMATIC FIT PID INFO
"Beta_Timing_KinFit": Float_t["NumCombos"] // = Path_Length/(c*Delta_t) //not present if p4-only fit
"ChiSq_Timing_KinFit": Float_t["NumCombos"] //only present if photon //not present if p4-only fit
 
//KINEMATIC FIT KINEMATICS //only present if kinfit performed
"X4_KinFit": TClonesArray(TLorentzVector["NumCombos"]) //not present if p4-only fit
"P4_KinFit": TClonesArray(TLorentzVector["NumCombos"])

//KINEMATICS: //At the decay vertex 
"X4": TLorentzVector["NumCombos"] //only present if has a detached vertex //kinematic fit result if kinfit performed, else reconstructed from detected particles
"PathLengthSigma": Float_t["NumCombos"] //only present if has a detached vertex and both vertices are fit
"P4_KinFit": TLorentzVector["NumCombos"] //only present if kinfit performed

//KINFIT KINEMATICS: //At its production vertex //only present if kinfit performed
"P4_KinFit": TLorentzVector["NumCombos"]

#include "ANALYSIS/DEventWriterROOT.h"
//In plugin brun():
const DEventWriterROOT* locEventWriterROOT = NULL;
locEventLoop->GetSingle(locEventWriterROOT);
locEventWriterROOT->Create_DataTrees(locEventLoop); //creates TTrees for all output-enabled DReactions
locEventWriterROOT->Create_ThrownTree("tree_b1pi_thrownmc.root"); //optional: create a ttree containing only the thrown data //string is output file name

//In plugin evnt()
const DEventWriterROOT* locEventWriterROOT = NULL;
locEventLoop->GetSingle(locEventWriterROOT);
locEventWriterROOT->Fill_DataTrees(locEventLoop, "b1pi_hists"); //string is the DReaction factory tag that the DReactions were created in

//In plugin evnt()
#include "ANALYSIS/DEventWriterROOT.h"
vector<const DEventWriterROOT*> locEventWriterROOTVector;
locEventLoop->Get(locEventWriterROOTVector); //creates the TTrees for all DReactions upon first call
locEventWriterROOTVector[0]->Fill_Tree(locEventLoop, locReaction, locParticleCombos);

//In plugin evnt()
const DEventWriterROOT* locEventWriterROOT = NULL;
locEventLoop->GetSingle(locEventWriterROOT);
locEventWriterROOT->Fill_ThrownTree(locEventLoop);

MyTree->Draw("PiMinus1__P4_Measured->Theta()"); //draws all particle combinations