helicityAngle.cc File Reference

#include "CommonTools/CandUtils/interface/helicityAngle.h"
#include "DataFormats/Candidate/interface/Candidate.h"
#include "CommonTools/CandUtils/interface/Booster.h"
#include <Math/VectorUtil.h>

Go to the source code of this file.

Functions
double	helicityAngle (const Candidate &cand)
double	helicityAngle (const reco::Candidate &mother, const reco::Candidate &daughter)
	return the helicity angle for two particles. More...

Function Documentation

helicityAngle() [1/2]

double helicityAngle

(

const reco::Candidate &

c

)

return the helicity angle of a two body decay with daughter automatically retreived Note: asserts if the candidate does not have two daughters

Definition at line 18 of file helicityAngle.cc.

                                            {
  assert(cand.numberOfDaughters() == 2);
  return helicityAngle(cand, *cand.daughter(0));
}

References cms::cuda::assert(), and helicityAngle().

helicityAngle() [2/2]

double helicityAngle	(	const reco::Candidate &	mother,
		const reco::Candidate &	daughter
	)

return the helicity angle for two particles.

helicityAngle

Utility function that returns the helicity angle It is defined as the angle between the candidate momentum and one of the daughters momentum in the mother's center-of-mass reference frame. This angle has a two-fold ambiguity (h, pi - h ), and by convention the angle smaller than pi/2 is chosen.

Author

Luca Lista, INFN

Version

Revision

1.7

Id

helicityAngle.h,v 1.7 2007/12/11 08:42:52 hegner Exp

Definition at line 9 of file helicityAngle.cc.

                                                                                 {
  Particle::Vector boost = mother.p4().BoostToCM();
  Particle::LorentzVector pdau = ROOT::Math::VectorUtil::boost(daughter.p4(), boost);
  double h = ROOT::Math::VectorUtil::Angle(pdau, boost);
  if (h > M_PI / 2)
    h = M_PI - h;
  return h;
}

References h, M_PI, and reco::Candidate::p4().

Referenced by helicityAngle().