EvtBtoXsgamma.cc

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//--------------------------------------------------------------------------
//
// Environment:
//      This software is part of the EvtGen package developed jointly
//      for the BaBar and CLEO collaborations.  If you use all or part
//      of it, please give an appropriate acknowledgement.
//
// Module: EvtBtoXsgamma.cc
//
// Description: Routine to perform two-body non-resonant B->Xs,gamma decays.
//              Set the first input parameter to 1 to use the Ali-Greub model,
//              or 2 to use the Kagan-Neubert model.
#include "../EvtGenBase/EvtPatches.hh"
 
//
// Modification history:
//
//    Mark Ian Williams       July 20, 2000       Module created
//    Mark Ian Williams       July 21, 2000       Module works
//    Mark Ian Williams       July 25, 2000       Works for all Xs modes
//    Mark Ian Williams       Aug  09, 2000       New values for mass minima
//    Mark Ian Williams       Sept 06, 2000       14 parameter M_Xs function
//    Mark Ian Williams       Sept 07, 2000       18 parameter M_Xs function
//    Mark Ian Williams       Sept 07, 2000       Tidied up the code
//    Mark Ian Williams       Sept 10, 2000       Updated parameters
//    Mark Ian Williams       Sept 11, 2000       Finalised code
//    Jane Tinslay            March 21, 2001      Re-worked so that you can choose
//                                                between the Ali-Greub and Kagan-Neubert
//                                                Modules.
//------------------------------------------------------------------------
//
 
#include "../EvtGenBase/EvtConst.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtReport.hh"
#include "EvtBtoXsgamma.hh"
#include "EvtBtoXsgammaAliGreub.hh"
#include "EvtBtoXsgammaFixedMass.hh"
#include "EvtBtoXsgammaFlatEnergy.hh"
#include "EvtBtoXsgammaKagan.hh"
#include <stdlib.h>
#include <string>
using std::endl;
 
EvtBtoXsgamma::~EvtBtoXsgamma() {
 
  delete _model;
  _model = 0;
}
 
void EvtBtoXsgamma::getName( std::string& model_name ) { model_name = "BTOXSGAMMA"; }
 
EvtDecayBase* EvtBtoXsgamma::clone() { return new EvtBtoXsgamma; }
 
void EvtBtoXsgamma::init() {
  // Arguments:
  //  0: Ali-Greub model = 1, Kagan model = 2
  // No more arguments for Ali-Greub model
  //  1:
  //  2:
  //  3:
 
  // check that at least one b->sg model has been selected
  if ( getNArg() == 0 )
  {
 
    report( ERROR, "EvtGen" ) << "EvtBtoXsgamma generator expected "
                              << " at least 1 argument but found: " << getNArg() << endl;
    report( ERROR, "EvtGen" ) << "Will terminate execution!" << endl;
    ::abort();
  }
}
 
void EvtBtoXsgamma::initProbMax() { noProbMax(); }
 
void EvtBtoXsgamma::decay( EvtParticle* p ) {
 
  // initialize here. -- its too damn slow otherwise.
 
  if ( _model == 0 )
  {
 
    if ( getArg( 0 ) == 1 ) _model = new EvtBtoXsgammaAliGreub();
    else if ( getArg( 0 ) == 2 ) _model = new EvtBtoXsgammaKagan();
    else if ( getArg( 0 ) == 3 ) _model = new EvtBtoXsgammaFixedMass();
    else if ( getArg( 0 ) == 4 ) _model = new EvtBtoXsgammaFlatEnergy();
    else
    {
      report( ERROR, "EvtGen" ) << "No valid EvtBtoXsgamma generator model selected "
                                << "Set arg(0) to 1 for Ali-Greub model or 2 for "
                                << " Kagan model or 3 for a fixed mass" << endl;
      report( ERROR, "EvtGen" ) << "Will terminate execution!" << endl;
      ::abort();
    }
    _model->init( getNArg(), getArgs() );
  }
 
  //  if ( p->getNDaug() != 0 ) {
  // Will end up here because maxrate multiplies by 1.2
  //  report(DEBUG,"EvtGen") << "In EvtBtoXsgamma: X_s daughters should not be here!"<<endl;
  //  return;
  //}
 
  double m_b;
  int    i;
  p->makeDaughters( getNDaug(), getDaugs() );
  EvtParticle* pdaug[MAX_DAUG];
 
  for ( i = 0; i < getNDaug(); i++ ) { pdaug[i] = p->getDaug( i ); }
 
  static EvtVector4R p4[MAX_DAUG];
  static double      mass[MAX_DAUG];
 
  m_b = p->mass();
 
  mass[1] = EvtPDL::getMass( getDaug( 1 ) );
 
  int Xscode = EvtPDL::getStdHep( getDaug( 0 ) );
 
  mass[0] = _model->GetMass( Xscode );
 
  EvtGenKine::PhaseSpace( getNDaug(), mass, p4, m_b );
 
  for ( i = 0; i < getNDaug(); i++ ) { pdaug[i]->init( getDaugs()[i], p4[i] ); }
}