source: git/modules/TrackSmearing.cc@ 952bbbc

/** \class TrackSmearing
 *
 *  Performs d0, dZ, p, Theta, Phi smearing of tracks.
 *
 *  \authors A. Hart, M. Selvaggi
 *
*/

#include "modules/TrackSmearing.h"

#include "classes/DelphesClasses.h"
#include "classes/DelphesFactory.h"
#include "classes/DelphesFormula.h"

#include "ExRootAnalysis/ExRootClassifier.h"
#include "ExRootAnalysis/ExRootFilter.h"
#include "ExRootAnalysis/ExRootResult.h"

#include "TDatabasePDG.h"
#include "TFile.h"
#include "TFormula.h"
#include "TLorentzVector.h"
#include "TMath.h"
#include "TObjArray.h"
#include "TProfile2D.h"
#include "TRandom3.h"
#include "TString.h"

#include <algorithm>
#include <iostream>
#include <sstream>
#include <stdexcept>

using namespace std;

//------------------------------------------------------------------------------

TrackSmearing::TrackSmearing() :
  fD0Formula(0), fDZFormula(0), fPFormula(0), fCtgThetaFormula(0), fPhiFormula(0), fItInputArray(0)
{
  fD0Formula = new DelphesFormula;
  fDZFormula = new DelphesFormula;
  fPFormula = new DelphesFormula;
  fCtgThetaFormula = new DelphesFormula;
  fPhiFormula = new DelphesFormula;
}

//------------------------------------------------------------------------------

TrackSmearing::~TrackSmearing()
{
  if(fD0Formula) delete fD0Formula;
  if(fDZFormula) delete fDZFormula;
  if(fPFormula) delete fPFormula;
  if(fCtgThetaFormula) delete fCtgThetaFormula;
  if(fPhiFormula) delete fPhiFormula;
}

//------------------------------------------------------------------------------

void TrackSmearing::Init()
{
  fBz = GetDouble("Bz", 0.0);

  // read resolution formula

  // !!! IF WE WANT TO KEEP ROOT INPUT !!!
  if(string(GetString("D0ResolutionFormula", "0.0")) != "0.0")
  {
    fD0Formula->Compile(GetString("D0ResolutionFormula", "0.0"));
    fUseD0Formula = true;
  }
  else
  {
    fD0ResolutionFile = GetString("D0ResolutionFile", "errors.root");
    fD0ResolutionHist = GetString("D0ResolutionHist", "d0");
    fUseD0Formula = false;
  }
  if(string(GetString("DZResolutionFormula", "0.0")) != "0.0")
  {
    fDZFormula->Compile(GetString("DZResolutionFormula", "0.0"));
    fUseDZFormula = true;
  }
  else
  {
    fDZResolutionFile = GetString("DZResolutionFile", "errors.root");
    fDZResolutionHist = GetString("DZResolutionHist", "dz");
    fUseDZFormula = false;
  }
  if(string(GetString("PResolutionFormula", "0.0")) != "0.0")
  {
    fPFormula->Compile(GetString("PResolutionFormula", "0.0"));
    fUsePFormula = true;
  }
  else
  {
    fPResolutionFile = GetString("PResolutionFile", "errors.root");
    fPResolutionHist = GetString("PResolutionHist", "p");
    fUsePFormula = false;
  }
  if(string(GetString("CtgThetaResolutionFormula", "0.0")) != "0.0")
  {
    fCtgThetaFormula->Compile(GetString("CtgThetaResolutionFormula", "0.0"));
    fUseCtgThetaFormula = true;
  }
  else
  {
    fCtgThetaResolutionFile = GetString("CtgThetaResolutionFile", "errors.root");
    fCtgThetaResolutionHist = GetString("CtgThetaResolutionHist", "ctgTheta");
    fUseCtgThetaFormula = false;
  }
  if(string(GetString("PhiResolutionFormula", "0.0")) != "0.0")
  {
    fPhiFormula->Compile(GetString("PhiResolutionFormula", "0.0"));
    fUsePhiFormula = true;
  }
  else
  {
    fPhiResolutionFile = GetString("PhiResolutionFile", "errors.root");
    fPhiResolutionHist = GetString("PhiResolutionHist", "phi");
    fUsePhiFormula = false;
  }

  fApplyToPileUp = GetBool("ApplyToPileUp", true);

  // import input array

  fInputArray = ImportArray(GetString("InputArray", "ParticlePropagator/stableParticles"));
  fItInputArray = fInputArray->MakeIterator();

  // import beamspot
  try
  {
    fBeamSpotInputArray = ImportArray(GetString("BeamSpotInputArray", "BeamSpotFilter/beamSpotParticle"));
  }
  catch(runtime_error &e)
  {
    fBeamSpotInputArray = 0;
  }

  // create output array

  fOutputArray = ExportArray(GetString("OutputArray", "stableParticles"));
}

//------------------------------------------------------------------------------

void TrackSmearing::Finish()
{
  if(fItInputArray) delete fItInputArray;
}

//------------------------------------------------------------------------------

void TrackSmearing::Process()
{
  Int_t iCandidate = 0;
  TLorentzVector beamSpotPosition;
  Candidate *candidate, *mother;
  Double_t pt, eta, e, m, d0, d0Error, trueD0, dz, dzError, trueDZ, p, pError, trueP, ctgTheta, ctgThetaError, trueCtgTheta, phi, phiError, truePhi;
  Double_t x, y, z, t, px, py, pz, theta;
  Double_t q, r;
  Double_t x_c, y_c, r_c, phi_0;
  Double_t rcu, rc2, xd, yd, zd;
  const Double_t c_light = 2.99792458E8;
  TProfile2D *d0ErrorHist = NULL,
             *dzErrorHist = NULL,
             *pErrorHist = NULL,
             *ctgThetaErrorHist = NULL,
             *phiErrorHist = NULL;

  if(!fBeamSpotInputArray || fBeamSpotInputArray->GetSize() == 0)
    beamSpotPosition.SetXYZT(0.0, 0.0, 0.0, 0.0);
  else
  {
    Candidate &beamSpotCandidate = *((Candidate *)fBeamSpotInputArray->At(0));
    beamSpotPosition = beamSpotCandidate.Position;
  }

  if(!fUseD0Formula)
  {
    TFile *fin = TFile::Open(fD0ResolutionFile.c_str());
    d0ErrorHist = (TProfile2D *)fin->Get(fD0ResolutionHist.c_str());
    d0ErrorHist->SetDirectory(0);
    fin->Close();
  }
  if(!fUseDZFormula)
  {
    TFile *fin = TFile::Open(fDZResolutionFile.c_str());
    dzErrorHist = (TProfile2D *)fin->Get(fDZResolutionHist.c_str());
    dzErrorHist->SetDirectory(0);
    fin->Close();
  }
  if(!fUsePFormula)
  {
    TFile *fin = TFile::Open(fPResolutionFile.c_str());
    pErrorHist = (TProfile2D *)fin->Get(fPResolutionHist.c_str());
    pErrorHist->SetDirectory(0);
    fin->Close();
  }
  if(!fUseCtgThetaFormula)
  {
    TFile *fin = TFile::Open(fCtgThetaResolutionFile.c_str());
    ctgThetaErrorHist = (TProfile2D *)fin->Get(fCtgThetaResolutionHist.c_str());
    ctgThetaErrorHist->SetDirectory(0);
    fin->Close();
  }
  if(!fUsePhiFormula)
  {
    TFile *fin = TFile::Open(fPhiResolutionFile.c_str());
    phiErrorHist = (TProfile2D *)fin->Get(fPhiResolutionHist.c_str());
    phiErrorHist->SetDirectory(0);
    fin->Close();
  }

  fItInputArray->Reset();
  while((candidate = static_cast<Candidate *>(fItInputArray->Next())))
  {

    const TLorentzVector &momentum = candidate->Momentum;
    const TLorentzVector &position = candidate->InitialPosition;

    pt = momentum.Pt();
    eta = momentum.Eta();
    e = momentum.E();
    m = momentum.M();

    d0 = trueD0 = candidate->D0;
    dz = trueDZ = candidate->DZ;

    p = trueP = candidate->P;
    ctgTheta = trueCtgTheta = candidate->CtgTheta;
    phi = truePhi = candidate->Phi;

    if(fUseD0Formula)
      d0Error = fD0Formula->Eval(pt, eta, phi, e, candidate);
    else
    {
      Int_t xbin, ybin;

      xbin = pt < d0ErrorHist->GetXaxis()->GetXmax() ? d0ErrorHist->GetXaxis()->FindBin(pt) : d0ErrorHist->GetXaxis()->GetBinCenter(d0ErrorHist->GetXaxis()->GetNbins());
      ybin = d0ErrorHist->GetYaxis()->FindBin(TMath::Abs(eta));
      d0Error = d0ErrorHist->GetBinContent(xbin, ybin);
      if(!d0Error)
        d0Error = -1.0;
    }
    if(d0Error < 0.0)
      continue;

    if(fUseDZFormula)
      dzError = fDZFormula->Eval(pt, eta, phi, e, candidate);
    else
    {
      Int_t xbin, ybin;

      xbin = pt < dzErrorHist->GetXaxis()->GetXmax() ? dzErrorHist->GetXaxis()->FindBin(pt) : dzErrorHist->GetXaxis()->GetBinCenter(dzErrorHist->GetXaxis()->GetNbins());
      ybin = dzErrorHist->GetYaxis()->FindBin(TMath::Abs(eta));
      dzError = dzErrorHist->GetBinContent(xbin, ybin);
      if(!dzError)
        dzError = -1.0;
    }
    if(dzError < 0.0)
      continue;

    if(fUsePFormula)
      pError = fPFormula->Eval(pt, eta, phi, e, candidate) * p;
    else
    {
      Int_t xbin, ybin;

      xbin = pt < pErrorHist->GetXaxis()->GetXmax() ? pErrorHist->GetXaxis()->FindBin(pt) : pErrorHist->GetXaxis()->GetBinCenter(pErrorHist->GetXaxis()->GetNbins());
      ybin = pErrorHist->GetYaxis()->FindBin(TMath::Abs(eta));
      pError = pErrorHist->GetBinContent(xbin, ybin) * p;
      if(!pError)
        pError = -1.0;
    }
    if(pError < 0.0)
      continue;

    if(fUseCtgThetaFormula)
      ctgThetaError = fCtgThetaFormula->Eval(pt, eta, phi, e, candidate);
    else
    {
      Int_t xbin, ybin;

      xbin = pt < ctgThetaErrorHist->GetXaxis()->GetXmax() ? ctgThetaErrorHist->GetXaxis()->FindBin(pt) : ctgThetaErrorHist->GetXaxis()->GetBinCenter(ctgThetaErrorHist->GetXaxis()->GetNbins());
      ybin = ctgThetaErrorHist->GetYaxis()->FindBin(TMath::Abs(eta));
      ctgThetaError = ctgThetaErrorHist->GetBinContent(xbin, ybin);
      if(!ctgThetaError)
        ctgThetaError = -1.0;
    }
    if(ctgThetaError < 0.0)
      continue;

    if(fUsePhiFormula)
      phiError = fPhiFormula->Eval(pt, eta, phi, e, candidate);
    else
    {
      Int_t xbin, ybin;

      xbin = pt < phiErrorHist->GetXaxis()->GetXmax() ? phiErrorHist->GetXaxis()->FindBin(pt) : phiErrorHist->GetXaxis()->GetBinCenter(phiErrorHist->GetXaxis()->GetNbins());
      ybin = phiErrorHist->GetYaxis()->FindBin(TMath::Abs(eta));
      phiError = phiErrorHist->GetBinContent(xbin, ybin);
      if(!phiError)
        phiError = -1.0;
    }
    if(phiError < 0.0)
      continue;

    if(fApplyToPileUp || !candidate->IsPU)
    {
      d0 = gRandom->Gaus(d0, d0Error);
      dz = gRandom->Gaus(dz, dzError);
      p = gRandom->Gaus(p, pError);
      ctgTheta = gRandom->Gaus(ctgTheta, ctgThetaError);
      phi = gRandom->Gaus(phi, phiError);
    }

    if(p < 0.0) continue;
    while(phi > TMath::Pi()) phi -= TMath::TwoPi();
    while(phi <= -TMath::Pi()) phi += TMath::TwoPi();

    mother = candidate;
    candidate = static_cast<Candidate *>(candidate->Clone());
    candidate->D0 = d0;
    candidate->DZ = dz;
    candidate->P = p;
    candidate->CtgTheta = ctgTheta;
    candidate->Phi = phi;

    theta = TMath::ACos(ctgTheta / TMath::Sqrt(1.0 + ctgTheta * ctgTheta));
    candidate->Momentum.SetPx(p * TMath::Cos(phi) * TMath::Sin(theta));
    candidate->Momentum.SetPy(p * TMath::Sin(phi) * TMath::Sin(theta));
    candidate->Momentum.SetPz(p * TMath::Cos(theta));
    candidate->Momentum.SetE(TMath::Sqrt(p*p + m*m));
    candidate->PT = candidate->Momentum.Pt();

    x = position.X();
    y = position.Y();
    z = position.Z();
    t = position.T();
    px = candidate->Momentum.Px();
    py = candidate->Momentum.Py();
    pz = candidate->Momentum.Pz();
    pt = candidate->Momentum.Pt();

    // -- solve for delta: d0' = ( (x+delta)*py' - (y+delta)*px' )/pt'

    candidate->InitialPosition.SetX(x + ((px * y - py * x + d0 * pt) / (py - px)));
    candidate->InitialPosition.SetY(y + ((px * y - py * x + d0 * pt) / (py - px)));
    x = candidate->InitialPosition.X();
    y = candidate->InitialPosition.Y();
    candidate->InitialPosition.SetZ(z + ((pz * (px * (x - beamSpotPosition.X()) + py * (y - beamSpotPosition.Y())) + pt * pt * (dz - z)) / (pt * pt)));
    z = candidate->InitialPosition.Z();

    candidate->InitialPosition.SetT(t);

    // update closest approach
    x *= 1.0E-3;
    y *= 1.0E-3;
    z *= 1.0E-3;

    q = candidate->Charge;

    r = pt / (q * fBz) * 1.0E9 / c_light; // in [m]
    phi_0 = TMath::ATan2(py, px); // [rad] in [-pi, pi]

    // 2. helix axis coordinates
    x_c = x + r * TMath::Sin(phi_0);
    y_c = y - r * TMath::Cos(phi_0);
    r_c = TMath::Hypot(x_c, y_c);

    rcu = TMath::Abs(r);
    rc2 = r_c * r_c;

    // calculate coordinates of closest approach to track circle in transverse plane xd, yd, zd
    xd = x_c * x_c * x_c - x_c * rcu * r_c + x_c * y_c * y_c;
    xd = (rc2 > 0.0) ? xd / rc2 : -999;
    yd = y_c * (-rcu * r_c + rc2);
    yd = (rc2 > 0.0) ? yd / rc2 : -999;
    zd = z + (TMath::Sqrt(xd * xd + yd * yd) - TMath::Sqrt(x * x + y * y)) * pz / pt;

    candidate->Xd = xd * 1.0E3;
    candidate->Yd = yd * 1.0E3;
    candidate->Zd = zd * 1.0E3;

    if(fApplyToPileUp || !candidate->IsPU)
    {
      candidate->ErrorD0 = d0Error;
      candidate->ErrorDZ = dzError;
      candidate->ErrorP = pError;
      candidate->ErrorCtgTheta = ctgThetaError;
      candidate->ErrorPhi = phiError;
      candidate->ErrorPT = ptError(p, ctgTheta, pError, ctgThetaError);
      candidate->TrackResolution = pError / p;
    }

    candidate->AddCandidate(mother);
    fOutputArray->Add(candidate);

    iCandidate++;
  }
}

Double_t TrackSmearing::ptError(const Double_t p, const Double_t ctgTheta, const Double_t dP, const Double_t dCtgTheta)
{
  Double_t a, b;
  a = (p * p * ctgTheta * ctgTheta * dCtgTheta * dCtgTheta) / ((ctgTheta * ctgTheta + 1) * (ctgTheta * ctgTheta + 1) * (ctgTheta * ctgTheta + 1));
  b = (dP * dP) / (ctgTheta * ctgTheta + 1);
  return sqrt(a + b);
}

//------------------------------------------------------------------------------