EvtHighSpinParticle.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: EvtHighSpinParticle.cc
//
// Description: Class to describe particles with spin>2.
//
// Modification history:
//
//    RYD   August 8, 2000           Module created
//
//------------------------------------------------------------------------
//
#include "EvtHighSpinParticle.hh"
#include "EvtPDL.hh"
#include "EvtPatches.hh"
#include "EvtSpinDensity.hh"
#include "EvtVector4R.hh"
#include "EvtdFunction.hh"
#include <assert.h>
#include <iostream>
#include <math.h>
 
EvtHighSpinParticle::~EvtHighSpinParticle() {}
 
void EvtHighSpinParticle::init( EvtId id, const EvtVector4R& p4 ) {
 
  _validP4 = true;
  setp( p4 );
  setpart_num( id );
 
  setLifetime();
}
 
EvtSpinDensity EvtHighSpinParticle::rotateToHelicityBasis() const {
 
  int n = EvtSpinType::getSpinStates( EvtPDL::getSpinType( getId() ) );
 
  EvtSpinDensity R;
  R.SetDiag( n );
 
  return R;
}
 
EvtSpinDensity EvtHighSpinParticle::rotateToHelicityBasis( double alpha, double beta,
                                                           double gamma ) const {
 
  int i, j;
 
  int n = EvtSpinType::getSpinStates( EvtPDL::getSpinType( getId() ) );
 
  EvtSpinDensity R;
  R.SetDim( n );
 
  int J2 = EvtSpinType::getSpin2( EvtPDL::getSpinType( getId() ) );
 
  assert( n == J2 + 1 );
 
  int* lambda2;
 
  lambda2 = new int[J2 + 1];
 
  for ( i = 0; i < J2 + 1; i++ ) { lambda2[i] = J2 - i * 2; }
 
  for ( i = 0; i < n; i++ )
  {
    for ( j = 0; j < n; j++ )
    {
      R.Set(
          i, j,
          EvtdFunction::d( J2, lambda2[j], lambda2[i], -beta ) *
              exp( EvtComplex( 0.0, -0.5 * ( alpha * lambda2[i] - gamma * lambda2[j] ) ) ) );
    }
  }
 
  delete[] lambda2;
 
  return R;
}