FML3PtSmearer Class Reference

#include <FML3PtSmearer.h>

List of all members.

Public Member Functions
	FML3PtSmearer (const RandomEngine *engine)
	Constructor.
math::XYZTLorentzVector	smear (math::XYZTLorentzVector simP4, math::XYZVector recP3) const
	smear the transverse momentum of a reco::Muon
	~FML3PtSmearer ()
	Destructor.
Private Member Functions
double	error (double thePt, double theEta) const
	smear the transverse momentum of a SimplL3MuGMTCand
double	funShift (double x) const
double	funSigma (double eta, double pt) const
double	funSigmaEta (double x) const
double	funSigmaPt (double x) const
double	shift (double thePt, double theEta) const
Private Attributes
const RandomEngine *	random
Static Private Attributes
static double	MuonMassSquared_ = 0.10565837*0.10565837

---

Detailed Description

Class to deal with the 'smearing' of the L3 muon transverse momentum. The output momentum is generated according to the probablility that a MC generated muon with the same pt leads to that momentum value in the GMT.

Author:

Andrea Perrotta Date: 25/05/2007

Definition at line 20 of file FML3PtSmearer.h.

---

Constructor & Destructor Documentation

FML3PtSmearer::FML3PtSmearer

(

const RandomEngine *

engine

)

Constructor.

Definition at line 13 of file FML3PtSmearer.cc.

  : random(engine)
{ }

FML3PtSmearer::~FML3PtSmearer

(

)

Destructor.

Definition at line 17 of file FML3PtSmearer.cc.

{}

---

Member Function Documentation

double FML3PtSmearer::error	(	double	thePt,
		double	theEta
	)		const [private]

smear the transverse momentum of a SimplL3MuGMTCand

Definition at line 54 of file FML3PtSmearer.cc.

References funSigma().

Referenced by smear().

                                                             {
  return funSigma(fabs(theEta),thePt)/thePt;
}

double FML3PtSmearer::funShift

(

double

x

)

const [private]

Definition at line 62 of file FML3PtSmearer.cc.

References ExpressReco_HICollisions_FallBack::x.

Referenced by shift().

                                             {
  if      (x<1.305) return 7.90897e-04;
  else if (x<1.82 ) return 9.52662e-02-1.12262e-01*x+3.05410e-02*x*x;
  else              return -7.9e-03;
  }

double FML3PtSmearer::funSigma	(	double	eta,
		double	pt
	)		const [private]

Definition at line 68 of file FML3PtSmearer.cc.

References funSigmaEta(), funSigmaPt(), and ExpressReco_HICollisions_FallBack::sigma.

Referenced by error().

                                                           {
  double sigma = funSigmaPt(pt) * funSigmaEta(eta);
  return sigma;
}

double FML3PtSmearer::funSigmaEta

(

double

x

)

const [private]

Definition at line 78 of file FML3PtSmearer.cc.

References funct::exp().

Referenced by funSigma().

                                                {
  if (x<0.94) return 2.27603e-02+1.23995e-06*exp(9.30755*x);
  else        return 2.99467e-02+1.86770e-05*exp(3.52319*x);
}

double FML3PtSmearer::funSigmaPt

(

double

x

)

const [private]

Definition at line 73 of file FML3PtSmearer.cc.

References ExpressReco_HICollisions_FallBack::x.

Referenced by funSigma().

                                               {
  if (x<444.) return 3.13349e-01+2.77853e-03*x+4.94289e-06*x*x-9.63359e-09*x*x*x;
  else        return 9.26294e-01+1.64896e-03*x;
}

double FML3PtSmearer::shift	(	double	thePt,
		double	theEta
	)		const [private]

Definition at line 58 of file FML3PtSmearer.cc.

References funShift().

Referenced by smear().

                                                             {
  return funShift(fabs(theEta));
}

math::XYZTLorentzVector FML3PtSmearer::smear	(	math::XYZTLorentzVector	simP4,
		math::XYZVector	recP3
	)		const

smear the transverse momentum of a reco::Muon

Definition at line 19 of file FML3PtSmearer.cc.

References error(), RandomEngine::gaussShoot(), MuonMassSquared_, random, shift(), and mathSSE::sqrt().

Referenced by ParamL3MuonProducer::produce().

                                                                                                  {
  double ptSim = std::sqrt(simP4.perp2());
  double invPtSim;
  if (ptSim>0.) invPtSim = 1./ptSim; 
  else { 
    // Better if we throw an exception here...
    simP4.SetPx(recP3.X());
    simP4.SetPy(recP3.Y());
    simP4.SetPz(recP3.Z());
    double muonEnergy=std::sqrt(simP4.P()*simP4.P()+MuonMassSquared_);
    simP4.SetE(muonEnergy);
    return simP4;
  }
  double etaSim = simP4.eta();
  double invPtNew = random->gaussShoot(invPtSim,error(ptSim,etaSim));
  invPtNew /= ( 1. + shift(ptSim,etaSim)*invPtNew);
  if (invPtNew>0.) {
    double invPtRec = std::sqrt(recP3.perp2());
    if (invPtRec>0) invPtRec = 1./invPtRec; else invPtRec=invPtSim;
    simP4.SetPx(recP3.x()*invPtRec/invPtNew);
    simP4.SetPy(recP3.y()*invPtRec/invPtNew);
    simP4.SetPz(recP3.z()*invPtRec/invPtNew);
    double muonEnergy=std::sqrt(simP4.P()*simP4.P()+MuonMassSquared_);
    simP4.SetE(muonEnergy);
  }
  else { 
    simP4.SetPx(recP3.x());
    simP4.SetPy(recP3.y());
    simP4.SetPz(recP3.z());
    double muonEnergy=std::sqrt(simP4.P()*simP4.P()+MuonMassSquared_);
    simP4.SetE(muonEnergy);
  }
  return simP4;
}

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Member Data Documentation

double FML3PtSmearer::MuonMassSquared_ = 0.10565837*0.10565837 [static, private]

Definition at line 35 of file FML3PtSmearer.h.

Referenced by smear().

const RandomEngine* FML3PtSmearer::random [private]

Definition at line 37 of file FML3PtSmearer.h.

Referenced by smear().