EvtCBTo3piMPP.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: EvtCBTo3piMPP.cc
//
// Description: Routine to decay B+/-->pi+ pi- pi+/-
//              and has CP violation.
//
// Modification history:
//
//    RYD/Versille     May 6, 1997         Module created
//
//------------------------------------------------------------------------
//
#include "EvtCBTo3piMPP.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtId.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtPatches.hh"
#include "../EvtGenBase/EvtReport.hh"
#include <stdlib.h>
#include <string>
 
// Below you will have do modify the declaration to be appropriate
// for your new routine for the calculation of the amplitude
 
extern "C" void evt3pionsmpp_( double*, int*, double*, double*, double*, double*, double*,
                               double*, double* );
 
EvtCBTo3piMPP::~EvtCBTo3piMPP() {}
 
void EvtCBTo3piMPP::getName( std::string& model_name ) { model_name = "CB3PI-MPP"; }
 
EvtDecayBase* EvtCBTo3piMPP::clone() { return new EvtCBTo3piMPP; }
 
void EvtCBTo3piMPP::init() {
 
  // check that there are 1 argument
  checkNArg( 1 );
  checkNDaug( 3 );
 
  checkSpinParent( EvtSpinType::SCALAR );
 
  checkSpinDaughter( 0, EvtSpinType::SCALAR );
  checkSpinDaughter( 1, EvtSpinType::SCALAR );
  checkSpinDaughter( 2, EvtSpinType::SCALAR );
}
 
void EvtCBTo3piMPP::initProbMax() { setProbMax( 1.5 ); }
 
void EvtCBTo3piMPP::decay( EvtParticle* p ) {
 
  // added by Lange Jan4,2000
  static EvtId BM = EvtPDL::getId( "B-" );
  static EvtId BP = EvtPDL::getId( "B+" );
 
  EvtParticle *pi1, *pi2, *pi3;
 
  p->makeDaughters( getNDaug(), getDaugs() );
  pi1 = p->getDaug( 0 );
  pi2 = p->getDaug( 1 );
  pi3 = p->getDaug( 2 );
 
  EvtVector4R p4[3];
  double      alpha = getArg( 0 );
 
  int iset;
 
  static int first = 1;
 
  if ( first == 1 )
  {
    iset  = 10000;
    first = 0;
  }
  else { iset = 0; }
 
  double p4pi1[4], p4pi2[4], p4pi3[4];
 
  double realA, imgA, realbarA, imgbarA;
 
  evt3pionsmpp_( &alpha, &iset, p4pi1, p4pi2, p4pi3, &realA, &imgA, &realbarA, &imgbarA );
 
  p4[0].set( p4pi1[3], p4pi1[0], p4pi1[1], p4pi1[2] );
  p4[1].set( p4pi2[3], p4pi2[0], p4pi2[1], p4pi2[2] );
  p4[2].set( p4pi3[3], p4pi3[0], p4pi3[1], p4pi3[2] );
 
  pi1->init( getDaug( 0 ), p4[0] );
  pi2->init( getDaug( 1 ), p4[1] );
  pi3->init( getDaug( 2 ), p4[2] );
 
  EvtComplex A( realA, imgA );
  EvtComplex Abar( realbarA, imgbarA );
 
  // amp is filled just to make sure the compiler will
  // do its job!! but one has to define amp differently
  //  if one wants the B+ or the B- to decay to 3pi!
  //
 
  EvtComplex amp;
  if ( p->getId() == BP ) { amp = A; }
  if ( p->getId() == BM ) { amp = Abar; }
 
  vertex( amp );
 
  return;
}