Top_Decaykin.h

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//
// $Id: Top_Decaykin.h,v 1.1 2011/05/26 09:46:53 mseidel Exp $
//
// 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