EvtFlatte.cpp

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#include "EvtGenBase/EvtFlatte.hh"

#include "EvtGenBase/EvtComplex.hh"
#include "EvtGenBase/EvtConst.hh"
#include "EvtGenBase/EvtKine.hh"
#include "EvtGenBase/EvtPatches.hh"
#include "EvtGenBase/EvtReport.hh"
#include "EvtGenBase/EvtVector4R.hh"

#include <math.h>

//operator

EvtFlatte& EvtFlatte::operator=( const EvtFlatte& n )
{
    if ( &n == this )
        return *this;
    _p4_p = n._p4_p;
    _p4_d1 = n._p4_d1;
    _p4_d2 = n._p4_d2;
    _ampl = n._ampl;
    _theta = n._theta;
    _mass = n._mass;
    _params = n._params;
    //  _m1a = n._m1a;
    //  _m1b = n._m1b;
    //  _g1 = n._g1;
    //  _m2a = n._m2a;
    //  _m2b = n._m2b;
    //  _g2 = n._g2;
    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
                      //                   double m1a, double m1b, double g1,
                      //                   double m2a, double m2b, double g2
                      ) :
    _p4_p( p4_p ),
    _p4_d1( p4_d1 ),
    _p4_d2( p4_d2 ),
    _ampl( ampl ),
    _theta( theta ),
    _mass( mass ),
    _params( params )
//  _m1a(m1a), _m1b(m1b), _g1(g1),
//  _m2a(m2a), _m2b(m2b), _g2(g2)
{
}

//amplitude function

EvtComplex EvtFlatte::resAmpl()
{
    double pi180inv = 1.0 / EvtConst::radToDegrees;

    //   EvtComplex ampl(cos(_theta*pi180inv), sin(_theta*pi180inv));
    //   ampl *= _ampl;

    // SCALARS ONLY
    double mR = ( _p4_d1 + _p4_d2 ).mass();

    EvtComplex w;

    for ( vector<EvtFlatteParam>::const_iterator param = _params.begin();
          param != _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 ) ) ) );
        //     cout << m1 << " " << mR << " " << w << endl;
    }

    EvtComplex denom = _mass * _mass - mR * mR - EvtComplex( 0, 1 ) * w;
    EvtComplex ampl = _ampl *
                      EvtComplex( cos( _theta * pi180inv ),
                                  sin( _theta * pi180inv ) ) /
                      denom;
    //  cout << abs(1/denom) << endl;
    return ampl;
}