EvtSVSCP.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: EvtSVSCP.cc
//
// Description: Routine to decay scalar -> vectors scalar
//              and has CP violation.
//
// Modification history:
//
//    RYD       Febuary 10, 1997       Module created
//
//------------------------------------------------------------------------
//
#include "EvtSVSCP.hh"
#include "../EvtGenBase/EvtCPUtil.hh"
#include "../EvtGenBase/EvtConst.hh"
#include "../EvtGenBase/EvtGenKine.hh"
#include "../EvtGenBase/EvtPDL.hh"
#include "../EvtGenBase/EvtParticle.hh"
#include "../EvtGenBase/EvtPatches.hh"
#include "../EvtGenBase/EvtReport.hh"
#include "../EvtGenBase/EvtVector4C.hh"
#include <stdlib.h>
#include <string>
 
EvtSVSCP::~EvtSVSCP() {}
 
void EvtSVSCP::getName( std::string& model_name ) { model_name = "SVS_CP"; }
 
EvtDecayBase* EvtSVSCP::clone() { return new EvtSVSCP; }
 
void EvtSVSCP::init() {
 
  // check that there are 7 arguments
  checkNArg( 7 );
  checkNDaug( 2 );
 
  checkSpinParent( EvtSpinType::SCALAR );
 
  checkSpinDaughter( 0, EvtSpinType::VECTOR );
  checkSpinDaughter( 1, EvtSpinType::SCALAR );
}
 
void EvtSVSCP::initProbMax() {
 
  // This is probably not quite right, but it should do as a start...
  // Anders
 
  setProbMax( 2 * ( getArg( 3 ) * getArg( 3 ) + getArg( 5 ) * getArg( 5 ) ) );
}
 
void EvtSVSCP::decay( EvtParticle* p ) {
 
  // added by Lange Jan4,2000
  static EvtId B0  = EvtPDL::getId( "B0" );
  static EvtId B0B = EvtPDL::getId( "anti-B0" );
 
  EvtParticle* v;
  p->initializePhaseSpace( getNDaug(), getDaugs() );
  v                 = p->getDaug( 0 );
  EvtVector4R momv  = v->getP4();
  EvtVector4R moms  = p->getDaug( 1 )->getP4();
  double      massv = v->mass();
  double      t;
  EvtId       other_b;
 
  EvtCPUtil::OtherB( p, t, other_b );
 
  EvtComplex amp;
 
  EvtComplex A, Abar;
 
  A    = EvtComplex( getArg( 3 ) * cos( getArg( 4 ) ), getArg( 3 ) * sin( getArg( 4 ) ) );
  Abar = EvtComplex( getArg( 5 ) * cos( getArg( 6 ) ), getArg( 5 ) * sin( getArg( 6 ) ) );
 
  if ( other_b == B0B )
  {
    amp = A * cos( getArg( 1 ) * t / ( 2 * EvtConst::c ) ) +
          EvtComplex( cos( -2.0 * getArg( 0 ) ), sin( -2.0 * getArg( 0 ) ) ) * getArg( 2 ) *
              EvtComplex( 0.0, 1.0 ) * Abar * sin( getArg( 1 ) * t / ( 2 * EvtConst::c ) );
  }
  if ( other_b == B0 )
  {
    amp = A * EvtComplex( cos( 2.0 * getArg( 0 ) ), sin( 2.0 * getArg( 0 ) ) ) *
              EvtComplex( 0.0, 1.0 ) * sin( getArg( 1 ) * t / ( 2 * EvtConst::c ) ) +
          getArg( 2 ) * Abar * cos( getArg( 1 ) * t / ( 2 * EvtConst::c ) );
  }
 
  EvtVector4R p4_parent;
 
  p4_parent = momv + moms;
 
  double norm = massv / ( momv.d3mag() * p4_parent.mass() );
 
  vertex( 0, amp * norm * p4_parent * ( v->epsParent( 0 ) ) );
  vertex( 1, amp * norm * p4_parent * ( v->epsParent( 1 ) ) );
  vertex( 2, amp * norm * p4_parent * ( v->epsParent( 2 ) ) );
 
  return;
}