EvtSVVCPLH.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) 1999      Caltech, UCSB
//
// Module: EvtSVVCPLH.cc
//
// Description: The decay of a scalar to two vector particles are
//              performed with CP violation and different widths for
//              the cpe even and od states. E.g. Bs->J/psi phi.
//
// Modification history:
//
//    RYD       November 5, 1999       Module created
//
//------------------------------------------------------------------------
//
#include "EvtSVVCPLH.hh"
#include "../EvtGenBase/EvtCPUtil.hh"
#include "../EvtGenBase/EvtConst.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 "EvtSVVHelAmp.hh"
#include <stdlib.h>
#include <string>
using std::endl;
 
EvtSVVCPLH::~EvtSVVCPLH() {}
 
void EvtSVVCPLH::getName( std::string& model_name ) { model_name = "SVV_CPLH"; }
 
EvtDecayBase* EvtSVVCPLH::clone() { return new EvtSVVCPLH; }
 
void EvtSVVCPLH::init() {
 
  // check that there are 9 arguments
  checkNArg( 9 );
  checkNDaug( 2 );
 
  checkSpinParent( EvtSpinType::SCALAR );
 
  checkSpinDaughter( 0, EvtSpinType::VECTOR );
  checkSpinDaughter( 1, EvtSpinType::VECTOR );
}
 
void EvtSVVCPLH::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 ) +
                    getArg( 7 ) * getArg( 7 ) ) );
}
 
void EvtSVVCPLH::decay( EvtParticle* p ) {
 
  // added by Lange Jan4,2000
  static EvtId BS0 = EvtPDL::getId( "B_s0" );
  static EvtId BSB = EvtPDL::getId( "anti-B_s0" );
 
  double t;
  EvtId  other_b;
 
  EvtCPUtil::OtherB( p, t, other_b );
 
  EvtComplex G0P, G1P, G1M;
 
  G1P = EvtComplex( getArg( 3 ) * cos( getArg( 4 ) ), getArg( 3 ) * sin( getArg( 4 ) ) );
  G0P = EvtComplex( getArg( 5 ) * cos( getArg( 6 ) ), getArg( 5 ) * sin( getArg( 6 ) ) );
  G1M = EvtComplex( getArg( 7 ) * cos( getArg( 8 ) ), getArg( 7 ) * sin( getArg( 8 ) ) );
 
  EvtComplex lambda_km = EvtComplex( cos( 2 * getArg( 0 ) ), sin( 2 * getArg( 0 ) ) );
 
  double cdmt = cos( getArg( 1 ) * t / ( 2 * EvtConst::c ) );
  double sdmt = sin( getArg( 1 ) * t / ( 2 * EvtConst::c ) );
 
  EvtComplex cG0P, cG1P, cG1M;
 
  static double ctauL = EvtPDL::getctau( EvtPDL::getId( "B_s0L" ) );
  static double ctauH = EvtPDL::getctau( EvtPDL::getId( "B_s0H" ) );
  static double ctau  = ctauL < ctauH ? ctauH : ctauL;
 
  // I'm not sure if the fabs() is right when t can be
  // negative as in the case of Bs produced coherently.
  double pt = 1;
  double mt = exp( -fabs( t * ( ctauL - ctauH ) / ( ctauL * ctauH ) ) );
 
  if ( other_b == BSB )
  {
    cG0P = pt * G0P * ( cdmt + lambda_km * EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
    cG1P = pt * G1P * ( cdmt + lambda_km * EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
    cG1M = mt * G1M * ( cdmt - lambda_km * EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
  }
  else if ( other_b == BS0 )
  {
    cG0P = pt * G0P * ( cdmt + ( 1.0 / lambda_km ) * EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
    cG1P = pt * G1P * ( cdmt + ( 1.0 / lambda_km ) * EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
    cG1M = -mt * G1M * ( cdmt - ( 1.0 / lambda_km ) * EvtComplex( 0.0, getArg( 2 ) * sdmt ) );
  }
  else
  {
    report( ERROR, "EvtGen" ) << "other_b was not BSB or BS0!" << endl;
    ::abort();
  }
 
  EvtComplex A0, AP, AM;
 
  A0 = cG0P / sqrt( 2.0 );
  AP = ( cG1P + cG1M ) / sqrt( 2.0 );
  AM = ( cG1P - cG1M ) / sqrt( 2.0 );
 
  EvtSVVHelAmp::SVVHel( p, _amp2, getDaug( 0 ), getDaug( 1 ), AP, A0, AM );
 
  return;
}