d2/d32/helicityAngle_8cc_source.html

// $Id: helicityAngle.cc,v 1.14 2007/12/11 08:42:53 hegner Exp $

#include "CommonTools/CandUtils/interface/helicityAngle.h"

#include "DataFormats/Candidate/interface/Candidate.h"

#include "CommonTools/CandUtils/interface/Booster.h"

#include <Math/VectorUtil.h>

using namespace reco;

using namespace std;


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

  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;

}


double helicityAngle(const Candidate& cand) {

  assert(cand.numberOfDaughters() == 2);

  return helicityAngle(cand, *cand.daughter(0));

}