EvtBToKpipiCP.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: EvtBToKpipiCP.cc
//
// Description: Routine to decay B->K pi pi
//              and has CP violation.
//       --- This is the routine to be called by the Main generator
//          to get the decay of B0    -->-- K+ pi- pi0
//          The decay proceeeds through three channels:
//          a) B0 -->-- K*+ pi-  ; K*+    -->-- K+ pi0
//          b)          K*0 pi0  ; K*0bar -->-- K+ pi-
//          c)          K-  rho+ ; rho+   -->-- pi+ pi0
//         It provides at the same time the CP conjugate decay
//                              B0bar -->-- K- pi+ pi0
//
// Modification history:
//
//    Versille     September, 1997         Module created
//
//------------------------------------------------------------------------
//
#include "EvtBToKpipiCP.hh"
#include "../EvtGenBase/EvtCPUtil.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>
 
extern "C" {
extern void evtkpipi_( double*, double*, int*, double*, double*, double*, double*, double*,
                       double*, double*, double* );
}
 
EvtBToKpipiCP::~EvtBToKpipiCP() {}
 
void EvtBToKpipiCP::getName( std::string& model_name ) { model_name = "BTOKPIPI_CP"; }
 
EvtDecayBase* EvtBToKpipiCP::clone() { return new EvtBToKpipiCP; }
 
void EvtBToKpipiCP::init() {
 
  // check that there are 3 arguments
  checkNArg( 3 );
  checkNDaug( 3 );
 
  checkSpinParent( EvtSpinType::SCALAR );
 
  checkSpinDaughter( 0, EvtSpinType::SCALAR );
  checkSpinDaughter( 1, EvtSpinType::SCALAR );
  checkSpinDaughter( 2, EvtSpinType::SCALAR );
}
 
void EvtBToKpipiCP::decay( EvtParticle* p ) {
 
  // added by Lange Jan4,2000
  static EvtId B0  = EvtPDL::getId( "B0" );
  static EvtId B0B = EvtPDL::getId( "anti-B0" );
 
  double t;
  EvtId  other_b;
 
  EvtCPUtil::OtherB( p, t, other_b );
 
  EvtParticle *Kp, *pim, *pi0;
 
  p->makeDaughters( getNDaug(), getDaugs() );
  Kp  = p->getDaug( 0 );
  pim = p->getDaug( 1 );
  pi0 = p->getDaug( 2 );
 
  EvtVector4R p4[3];
 
  // double dm=getArg(0);
  double alpha = getArg( 1 );
  double beta  = getArg( 2 );
  int    iset;
 
  static int first = 1;
 
  if ( first == 1 )
  {
    iset  = 10000;
    first = 0;
  }
  else { iset = 0; }
 
  double p4Kplus[4], p4piminus[4], p4gamm1[4], p4gamm2[4];
 
  double realA, imgA, realbarA, imgbarA;
 
  evtkpipi_( &alpha, &beta, &iset, p4Kplus, p4piminus, p4gamm1, p4gamm2, &realA, &imgA,
             &realbarA, &imgbarA );
 
  p4[0].set( p4Kplus[3], p4Kplus[0], p4Kplus[1], p4Kplus[2] );
  p4[1].set( p4piminus[3], p4piminus[0], p4piminus[1], p4piminus[2] );
  p4[2].set( p4gamm1[3] + p4gamm2[3], p4gamm1[0] + p4gamm2[0], p4gamm1[1] + p4gamm2[1],
             p4gamm1[2] + p4gamm2[2] );
 
  Kp->init( getDaug( 0 ), p4[0] );
  pim->init( getDaug( 1 ), p4[1] );
  pi0->init( getDaug( 2 ), p4[2] );
 
  EvtComplex amp;
 
  EvtComplex A( realA, imgA );
  EvtComplex Abar( realbarA, imgbarA );
 
  if ( other_b == B0B ) { amp = Abar; }
  if ( other_b == B0 ) { amp = A; }
 
  vertex( amp );
 
  return;
}