EvtSll.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: EvtSll.cc
//
// Description: The decay of a scalar meson to two leptons,
//              or generally, two spin 1/2 particles.
//              E.g., B0 -> tau+ tau-
//
// Modification history:
//
//    SHY       April 23, 1997       Module created
//
//------------------------------------------------------------------------
//
#include "EvtSll.hh"
#include "../EvtGenBase/EvtDiracSpinor.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 <iostream>
#include <stdlib.h>
#include <string>
 
EvtSll::~EvtSll() {}
 
void EvtSll::getName( std::string& model_name ) { model_name = "SLL"; }
 
EvtDecayBase* EvtSll::clone() { return new EvtSll; }
 
void EvtSll::init() {
 
  // check that there are 0 arguments
  checkNArg( 0 );
  checkNDaug( 2 );
 
  checkSpinParent( EvtSpinType::SCALAR );
 
  checkSpinDaughter( 0, EvtSpinType::DIRAC );
  checkSpinDaughter( 1, EvtSpinType::DIRAC );
}
 
void EvtSll::decay( EvtParticle* p ) {
 
  p->initializePhaseSpace( getNDaug(), getDaugs() );
 
  EvtParticle *l1, *l2;
  l1 = p->getDaug( 0 );
  l2 = p->getDaug( 1 );
  EvtVector4R p4_p;
  p4_p.set( p->mass(), 0.0, 0.0, 0.0 );
 
  EvtVector4C l11, l12, l21, l22;
 
  l11 = EvtLeptonVACurrent( l1->spParent( 0 ), l2->spParent( 0 ) );
  l12 = EvtLeptonVACurrent( l1->spParent( 0 ), l2->spParent( 1 ) );
  l21 = EvtLeptonVACurrent( l1->spParent( 1 ), l2->spParent( 0 ) );
  l22 = EvtLeptonVACurrent( l1->spParent( 1 ), l2->spParent( 1 ) );
 
  vertex( 0, 0, p4_p * l11 );
  vertex( 0, 1, p4_p * l12 );
  vertex( 1, 0, p4_p * l21 );
  vertex( 1, 1, p4_p * l22 );
 
  return;
}