// ResonanceDecays.h is a part of the PYTHIA event generator.
// Copyright (C) 2008 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.

// This file contains the main class for performing resonance decays.
// ResonanceDecays: handles the sequential decay of resonances in process.

#ifndef Pythia8_ResonanceDecays_H
#define Pythia8_ResonanceDecays_H

#include "Basics.h"
#include "Event.h"
#include "Info.h"
#include "ParticleData.h"
#include "PythiaStdlib.h"
#include "ResonanceWidths.h"
#include "Settings.h"

namespace Pythia8 {
  
//**************************************************************************

// The ResonanceDecays class handles the sequential decay of resonances
// that are part of the hard process (t, W, Z, H, SUSY,...).

class ResonanceDecays {

public:

  // Constructor. 
  ResonanceDecays() {} 

  // Store pointer to Info for error messages.
  void init(Info* infoPtrIn) {infoPtr = infoPtrIn;}
 
  // Generate the next decay sequence.
  bool next( Event& process); 

private: 

  // Constants: could only be changed in the code itself.
  static const int    NTRYCHANNEL, NTRYMASSES;
  static const double MSAFETY, WIDTHCUT, TINY, WTCORRECTION[11];

  // Pointer to various information on the generation.
  Info* infoPtr;

  // Select masses of decay products.
  bool pickMasses(); 

  // Select colours of decay products.
  bool pickColours(int iDec, Event& process);

  // Select kinematics isotropic in phase space.
  bool pickKinematics();

  // Flavour, colour and momentum information.
  int            id0, mult;
  double         m0;
  vector<int>    idProd, cols, acols;
  vector<double> mProd;
  vector<Vec4>   pProd;

};

//**************************************************************************

} // end namespace Pythia8

#endif // Pythia8_ResonanceDecays_H