EvtFlatQ2.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.
//
// Copyright Information: See EvtGen/COPYRIGHT
//      Copyright (C) 1998      Caltech, UCSB
//
// Module: EvtFlatQ2.cc
//
// Description: B->Xu l nu with flat q2 distribution
//
// Modification history:
//
//    David Cote, U. de Montreal, 11/02/2003    Module created
//
//------------------------------------------------------------------------
//
#include "EvtFlatQ2.hh"
#include "../EvtGenBase/EvtPatches.hh"
 
#include "../EvtGenBase/EvtDiracSpinor.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtReport.hh"
#include "../EvtGenBase/EvtTensor4C.hh"
#include "../EvtGenBase/EvtVector4C.hh"
#include <fstream>
#include <stdio.h>
#include <stdlib.h>
#include <string>
using std::fstream;
 
EvtFlatQ2::~EvtFlatQ2() {}
 
void EvtFlatQ2::getName( std::string& model_name ) { model_name = "FLATQ2"; }
 
EvtDecayBase* EvtFlatQ2::clone() { return new EvtFlatQ2; }
 
void EvtFlatQ2::initProbMax() { setProbMax( 100 ); }
 
void EvtFlatQ2::init() {
 
  // check that there are 0 arguments
  checkNArg( 0 );
  checkNDaug( 3 );
 
  // We expect B->X l nu events
  checkSpinParent( EvtSpinType::SCALAR );
  checkSpinDaughter( 1, EvtSpinType::DIRAC );
  checkSpinDaughter( 2, EvtSpinType::NEUTRINO );
}
 
void EvtFlatQ2::decay( EvtParticle* p ) {
 
  p->initializePhaseSpace( getNDaug(), getDaugs() );
 
  EvtVector4R p4Xu   = p->getDaug( 0 )->getP4();
  double      pXu_x2 = p4Xu.get( 1 ) * p4Xu.get( 1 );
  double      pXu_y2 = p4Xu.get( 2 ) * p4Xu.get( 2 );
  double      pXu_z2 = p4Xu.get( 3 ) * p4Xu.get( 3 );
  double      pXu    = sqrt( pXu_x2 + pXu_y2 + pXu_z2 );
  double      prob   = 1 / pXu;
 
  if ( pXu > 0.01 ) setProb( prob );
 
  return;
}