VBuilders.h

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//=========================================================================
// VBuilders.h
//
// Functors for building various quantities from grid points. They are
// intended for use with "KernelRecombinationAlg" or similar templated
// classes.
//
// I. Volobouev
// March 2010
//=========================================================================

#ifndef RecoJets_FFTJetAlgorithms_VBuilders_h
#define RecoJets_FFTJetAlgorithms_VBuilders_h

#include <cmath>

#include "DataFormats/Math/interface/LorentzVector.h"

namespace fftjetcms {
  struct PtEtaP4Builder {
    inline math::XYZTLorentzVector operator()(const double pt, const double eta, const double phi) const {
      const double px = pt * cos(phi);
      const double py = pt * sin(phi);
      const double pz = pt * sinh(eta);
      const double e = sqrt(px * px + py * py + pz * pz);
      return math::XYZTLorentzVector(px, py, pz, e);
    }
  };

  struct EnergyEtaP4Builder {
    inline math::XYZTLorentzVector operator()(const double e, const double eta, const double phi) const {
      // There is no mass associated with this energy... We will
      // assume that the mass is 0 and proceed as if the energy
      // is the momentum.
      const double pt = e / cosh(eta);
      return math::XYZTLorentzVector(pt * cos(phi), pt * sin(phi), pt * sinh(eta), e);
    }
  };
}  // namespace fftjetcms

#endif  // RecoJets_FFTJetAlgorithms_VBuilders_h