ForwardProton.h

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/****************************************************************************
 * Authors:
 *   Jan Kašpar
 *   Laurent Forthomme
 ****************************************************************************/

#ifndef DataFormats_ProtonReco_ForwardProton_h
#define DataFormats_ProtonReco_ForwardProton_h

#include "DataFormats/Math/interface/Error.h"
#include "DataFormats/Math/interface/Point3D.h"
#include "DataFormats/Math/interface/Vector3D.h"

#include "DataFormats/Common/interface/RefVector.h"

#include "DataFormats/CTPPSReco/interface/CTPPSLocalTrackLiteFwd.h"

namespace reco {
  class ForwardProton {
  public:
    enum { dimension = 5 };
    enum struct Index { xi, th_x, vtx_x, th_y, vtx_y, num_indices = dimension };
    typedef math::ErrorF<dimension>::type CovarianceMatrix;
    typedef math::XYZVectorF Vector;
    typedef math::XYZPointF Point;
    enum class ReconstructionMethod { invalid = -1, singleRP, multiRP };

  public:
    ForwardProton();
    ForwardProton(double chi2,
                  double ndof,
                  const Point& vtx,
                  const Vector& momentum,
                  float xi,
                  const CovarianceMatrix& cov,
                  ReconstructionMethod method,
                  const CTPPSLocalTrackLiteRefVector& local_tracks,
                  bool valid,
                  const float time = 0.,
                  const float time_err = 0.);

    const Point& vertex() const { return vertex_; }
    float vx() const { return vertex_.x(); }
    float vy() const { return vertex_.y(); }
    float vz() const { return vertex_.z(); }
    const Vector& momentum() const { return momentum_; }
    float p() const { return momentum_.r(); }
    float pt() const { return momentum_.rho(); }
    float px() const { return momentum_.x(); }
    float py() const { return momentum_.y(); }
    float pz() const { return momentum_.z(); }

    float chi2() const { return chi2_; }
    unsigned int ndof() const { return ndof_; }
    float normalizedChi2() const { return (ndof_ != 0) ? chi2_ / ndof_ : chi2_ * 1.e6; }

    float xi() const { return xi_; }
    float thetaX() const { return px() / p(); }
    float thetaY() const { return py() / p(); }

    // vertex position can be obtained via TrackBase::vx() and vy() functions

    double error(Index i) const { return sqrt(covariance_((unsigned int)i, (unsigned int)i)); }

    float xiError() const { return error(Index::xi); }
    float thetaXError() const { return error(Index::th_x); }
    float thetaYError() const { return error(Index::th_y); }
    float vxError() const { return error(Index::vtx_x); }
    float vyError() const { return error(Index::vtx_y); }

    static float mass() { return mass_; }

    static float calculateT(double beam_mom, double proton_mom, double theta);

    float t() const;

    float time() const { return time_; }
    void setTime(float time) { time_ = time; }

    float timeError() const { return time_err_; }
    void setTimeError(float time_err) { time_err_ = time_err; }

    void setValidFit(bool valid = true) { valid_fit_ = valid; }
    bool validFit() const { return valid_fit_; }

    void setMethod(const ReconstructionMethod& method) { method_ = method; }
    ReconstructionMethod method() const { return method_; }

    void setContributingLocalTracks(const CTPPSLocalTrackLiteRefVector& v) { contributing_local_tracks_ = v; }
    const CTPPSLocalTrackLiteRefVector& contributingLocalTracks() const { return contributing_local_tracks_; }

    enum class LHCSector { invalid = -1, sector45, sector56 };
    LHCSector lhcSector() const {
      if (pz() < 0.)
        return LHCSector::sector56;
      if (pz() > 0.)
        return LHCSector::sector45;
      return LHCSector::invalid;
    }

  private:
    static constexpr float mass_ = 0.938272046;        
    static constexpr float massSquared_ = 0.88035443;  

    Point vertex_;
    Vector momentum_;
    float time_;
    float time_err_;
    float xi_;
    CovarianceMatrix covariance_;
    float chi2_;
    unsigned int ndof_;
    bool valid_fit_;
    ReconstructionMethod method_;
    CTPPSLocalTrackLiteRefVector contributing_local_tracks_;
  };
}  // namespace reco

#endif