Top_Decaykin.h

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//
//
// File: hitfit/Top_Decaykin.h
// Purpose: Calculate some kinematic quantities for ttbar events.
// Created: Jul, 2000, sss, based on run 1 mass analysis code.
//
// CMSSW File      : interface/Top_Decaykin.h
// Original Author : Scott Stuart Snyder <snyder@bnl.gov> for D0
// Imported to CMSSW by Haryo Sumowidagdo <Suharyo.Sumowidagdo@cern.ch>
//

#ifndef HITFIT_TOP_DECAYKIN_H
#define HITFIT_TOP_DECAYKIN_H

#include "CLHEP/Vector/Boost.h"

#include "TopQuarkAnalysis/TopHitFit/interface/fourvec.h"
#include <iosfwd>

namespace hitfit {

  class Lepjets_Event;

  class Top_Decaykin
  //
  // Purpose: Calculate some kinematic quantities for ttbar events.
  //          This class has no state --- just static member functions.
  //
  {
  public:
    // Solve for the longitudinal z-momentum that makes the leptonic
    // top have mass TMASS.
    static bool solve_nu_tmass(const Lepjets_Event& ev, double tmass, double& nuz1, double& nuz2);

    // Solve for the longitudinal z-momentum that makes the leptonic
    // top have mass TMASS, with imaginary component returned.
    static bool solve_nu_tmass(
        const Lepjets_Event& ev, double tmass, double& re_nuz1, double& im_nuz1, double& re_nuz2, double& im_nuz2);

    // Solve for the longitudinal z-momentum that makes the leptonic
    // W have mass WMASS.
    static bool solve_nu(const Lepjets_Event& ev, double wmass, double& nuz1, double& nuz2);

    // Solve for the longitudinal z-momentum that makes the leptonic
    // W have mass WMASS, with imaginary component returned.
    static bool solve_nu(
        const Lepjets_Event& ev, double wmass, double& re_nuz1, double& im_nuz1, double& re_nuz2, double& im_nuz2);

    // Sum up the appropriate 4-vectors to find the hadronic W.
    static Fourvec hadw(const Lepjets_Event& ev);

    // Find the higher pT jet from hadronic W
    static Fourvec hadw1(const Lepjets_Event& ev);

    // Find the lower pT jet from hadronic W
    static Fourvec hadw2(const Lepjets_Event& ev);

    // Sum up the appropriate 4-vectors to find the leptonic W.
    static Fourvec lepw(const Lepjets_Event& ev);

    // Sum up the appropriate 4-vectors to find the hadronic t.
    static Fourvec hadt(const Lepjets_Event& ev);

    // Sum up the appropriate 4-vectors to find the leptonic t.
    static Fourvec lept(const Lepjets_Event& ev);

    // Print kinematic information for EV.
    static std::ostream& dump_ev(std::ostream& s, const Lepjets_Event& ev);

    // Solve cos theta star
    static double cos_theta_star(const Fourvec& fermion, const Fourvec& W, const Fourvec& top);

    // Solve cos theta star in lepton side of lepton+jets event
    static double cos_theta_star(const Lepjets_Event& ev);

    // Solve cos theta star in lepton side of lepton+jets event
    static double cos_theta_star_lept(const Lepjets_Event& ev);

    // Solve cos theta star in hadronic side of lepton+jets event
    static double cos_theta_star_hadt(const Lepjets_Event& ev);
  };

}  // namespace hitfit

#endif  // not HITFIT_TOP_DECAYKIN_H