EvtFlatte.cpp

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#include "EvtGenBase/EvtFlatte.hh"
 
#include "EvtGenBase/EvtComplex.hh"
#include "EvtGenBase/EvtConst.hh"
#include "EvtGenBase/EvtKine.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtVector4R.hh"
 
#include <math.h>
 
//operator
 
EvtFlatte& EvtFlatte::operator=( const EvtFlatte& n )
{
    if ( &n == this )
        return *this;
    m_p4_p = n.m_p4_p;
    m_p4_d1 = n.m_p4_d1;
    m_p4_d2 = n.m_p4_d2;
    m_ampl = n.m_ampl;
    m_theta = n.m_theta;
    m_mass = n.m_mass;
    m_params = n.m_params;
    return *this;
}
 
//constructor
 
EvtFlatte::EvtFlatte( const EvtVector4R& p4_p, const EvtVector4R& p4_d1,
                      const EvtVector4R& p4_d2, double ampl, double theta,
                      double mass, vector<EvtFlatteParam>& params ) :
    m_p4_p( p4_p ),
    m_p4_d1( p4_d1 ),
    m_p4_d2( p4_d2 ),
    m_ampl( ampl ),
    m_theta( theta ),
    m_mass( mass ),
    m_params( params )
{
}
 
//amplitude function
 
EvtComplex EvtFlatte::resAmpl()
{
    double pi180inv = 1.0 / EvtConst::radToDegrees;
 
    // SCALARS ONLY
    double mR = ( m_p4_d1 + m_p4_d2 ).mass();
 
    EvtComplex w;
 
    for ( vector<EvtFlatteParam>::const_iterator param = m_params.begin();
          param != m_params.end(); ++param ) {
        double m1 = ( *param ).m1();
        double m2 = ( *param ).m2();
        double g = ( *param ).g();
        w += ( g * g *
               sqrtCplx( ( 1 - ( ( m1 - m2 ) * ( m1 - m2 ) ) / ( mR * mR ) ) *
                         ( 1 - ( ( m1 + m2 ) * ( m1 + m2 ) ) / ( mR * mR ) ) ) );
    }
 
    EvtComplex denom = m_mass * m_mass - mR * mR - EvtComplex( 0, 1 ) * w;
    EvtComplex ampl = m_ampl *
                      EvtComplex( cos( m_theta * pi180inv ),
                                  sin( m_theta * pi180inv ) ) /
                      denom;
    return ampl;
}