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EvtTensorParticle.cpp
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EvtTensorParticle.cpp
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/***********************************************************************
* Copyright 1998-2020 CERN for the benefit of the EvtGen authors *
* *
* This file is part of EvtGen. *
* *
* EvtGen is free software: you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation, either version 3 of the License, or *
* (at your option) any later version. *
* *
* EvtGen is distributed in the hope that it will be useful, *
* but WITHOUT ANY WARRANTY; without even the implied warranty of *
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
* GNU General Public License for more details. *
* *
* You should have received a copy of the GNU General Public License *
* along with EvtGen. If not, see <https://www.gnu.org/licenses/>. *
***********************************************************************/
#include "EvtGenBase/EvtTensorParticle.hh"
#include "EvtGenBase/EvtComplex.hh"
#include "EvtGenBase/EvtPatches.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtTensor4C.hh"
#include "EvtGenBase/EvtVector4C.hh"
#include "EvtGenBase/EvtVector4R.hh"
#include <cassert>
#include <iostream>
#include <math.h>
#include <stdlib.h>
void EvtTensorParticle::init( EvtId part_n, const EvtVector4R& p4 )
{
init( part_n, p4.get( 0 ), p4.get( 1 ), p4.get( 2 ), p4.get( 3 ) );
setLifetime();
}
void EvtTensorParticle::init( EvtId part_n, double e, double px, double py,
double pz )
{
m_validP4 = true;
setp( e, px, py, pz );
setpart_num( part_n );
m_eps[0].setdiag( 0.0, -1.0 / sqrt( 6.0 ), -1.0 / sqrt( 6.0 ),
2.0 / sqrt( 6.0 ) );
m_eps[1].setdiag( 0.0, 1.0 / sqrt( 2.0 ), -1.0 / sqrt( 2.0 ), 0.0 );
m_eps[2].setdiag( 0.0, 0.0, 0.0, 0.0 );
m_eps[3].setdiag( 0.0, 0.0, 0.0, 0.0 );
m_eps[4].setdiag( 0.0, 0.0, 0.0, 0.0 );
m_eps[2].set( 1, 2, EvtComplex( 1.0 / sqrt( 2.0 ), 0.0 ) );
m_eps[2].set( 2, 1, EvtComplex( 1.0 / sqrt( 2.0 ), 0.0 ) );
m_eps[3].set( 1, 3, EvtComplex( 1.0 / sqrt( 2.0 ), 0.0 ) );
m_eps[3].set( 3, 1, EvtComplex( 1.0 / sqrt( 2.0 ), 0.0 ) );
m_eps[4].set( 2, 3, EvtComplex( 1.0 / sqrt( 2.0 ), 0.0 ) );
m_eps[4].set( 3, 2, EvtComplex( 1.0 / sqrt( 2.0 ), 0.0 ) );
setLifetime();
}
void EvtTensorParticle::init( EvtId part_n, const EvtVector4R& p4,
const EvtTensor4C& epsin1,
const EvtTensor4C& epsin2,
const EvtTensor4C& epsin3,
const EvtTensor4C& epsin4,
const EvtTensor4C& epsin5 )
{
m_validP4 = true;
setp( p4 );
setpart_num( part_n );
m_eps[0] = epsin1;
m_eps[1] = epsin2;
m_eps[2] = epsin3;
m_eps[3] = epsin4;
m_eps[4] = epsin5;
setLifetime();
}
EvtTensor4C EvtTensorParticle::epsTensorParent( int i ) const
{
assert( i >= 0 && i < m_eps.size() );
return boostTo( m_eps[i], this->getP4() );
}
EvtTensor4C EvtTensorParticle::epsTensor( int i ) const
{
assert( i >= 0 && i < m_eps.size() );
return m_eps[i];
}
EvtSpinDensity EvtTensorParticle::rotateToHelicityBasis() const
{
static EvtVector4C eplus( 0.0, -1.0 / sqrt( 2.0 ),
EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
static EvtVector4C ezero( 0.0, 0.0, 0.0, 1.0 );
static EvtVector4C eminus( 0.0, 1.0 / sqrt( 2.0 ),
EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
static EvtTensor4C dPpp( EvtGenFunctions::directProd( eplus, eplus ) );
static EvtTensor4C dPp0( EvtGenFunctions::directProd( eplus, ezero ) );
static EvtTensor4C dP0p( EvtGenFunctions::directProd( ezero, eplus ) );
static EvtTensor4C dPpm( EvtGenFunctions::directProd( eplus, eminus ) );
static EvtTensor4C dP00( EvtGenFunctions::directProd( ezero, ezero ) );
static EvtTensor4C dPmp( EvtGenFunctions::directProd( eminus, eplus ) );
static EvtTensor4C dPmm( EvtGenFunctions::directProd( eminus, eminus ) );
static EvtTensor4C dPm0( EvtGenFunctions::directProd( eminus, ezero ) );
static EvtTensor4C dP0m( EvtGenFunctions::directProd( ezero, eminus ) );
static EvtTensor4C es0( conj( dPpp ) );
static EvtTensor4C es1(
conj( ( 1 / sqrt( 2.0 ) ) * dPp0 + ( 1 / sqrt( 2.0 ) ) * dP0p ) );
static EvtTensor4C es2( conj( ( 1 / sqrt( 6.0 ) ) * dPpm +
( 2 / sqrt( 6.0 ) ) * dP00 +
( 1 / sqrt( 6.0 ) ) * dPmp ) );
static EvtTensor4C es3(
conj( ( 1 / sqrt( 2.0 ) ) * dPm0 + ( 1 / sqrt( 2.0 ) ) * dP0m ) );
static EvtTensor4C es4( conj( dPmm ) );
EvtSpinDensity R;
R.setDim( 5 );
for ( int j = 0; j < 5; j++ ) {
R.set( 0, j, cont( es0, m_eps[j] ) );
R.set( 1, j, cont( es1, m_eps[j] ) );
R.set( 2, j, cont( es2, m_eps[j] ) );
R.set( 3, j, cont( es3, m_eps[j] ) );
R.set( 4, j, cont( es4, m_eps[j] ) );
}
return R;
}
EvtSpinDensity EvtTensorParticle::rotateToHelicityBasis( double alpha,
double beta,
double gamma ) const
{
EvtTensor4C es[5];
static EvtVector4C eplus( 0.0, -1.0 / sqrt( 2.0 ),
EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
static EvtVector4C ezero( 0.0, 0.0, 0.0, 1.0 );
static EvtVector4C eminus( 0.0, 1.0 / sqrt( 2.0 ),
EvtComplex( 0.0, -1.0 / sqrt( 2.0 ) ), 0.0 );
eplus.applyRotateEuler( alpha, beta, gamma );
ezero.applyRotateEuler( alpha, beta, gamma );
eminus.applyRotateEuler( alpha, beta, gamma );
for ( int i = 0; i < 5; i++ )
es[i].zero();
es[0] = EvtGenFunctions::directProd( eplus, eplus );
es[1] = ( 1 / sqrt( 2.0 ) ) * EvtGenFunctions::directProd( eplus, ezero ) +
( 1 / sqrt( 2.0 ) ) * EvtGenFunctions::directProd( ezero, eplus );
es[2] = ( 1 / sqrt( 6.0 ) ) * EvtGenFunctions::directProd( eplus, eminus ) +
( 2 / sqrt( 6.0 ) ) * EvtGenFunctions::directProd( ezero, ezero ) +
( 1 / sqrt( 6.0 ) ) * EvtGenFunctions::directProd( eminus, eplus );
es[3] = ( 1 / sqrt( 2.0 ) ) * EvtGenFunctions::directProd( eminus, ezero ) +
( 1 / sqrt( 2.0 ) ) * EvtGenFunctions::directProd( ezero, eminus );
es[4] = EvtGenFunctions::directProd( eminus, eminus );
for ( int i = 0; i < 5; i++ )
es[i] = conj( es[i] );
EvtSpinDensity R;
R.setDim( 5 );
for ( int i = 0; i < 5; i++ )
for ( int j = 0; j < 5; j++ )
R.set( i, j, cont( es[i], m_eps[j] ) );
return R;
}

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