EvtPFermi.cpp

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#include "EvtGenModels/EvtPFermi.hh"
 
#include "EvtGenBase/EvtReport.hh"
 
#include <math.h>
#include <stdlib.h>
 
//----------------
// Constructors --
//----------------
 
//for DFN model
EvtPFermi::EvtPFermi( const double& a, const double& mB, const double& mb )
{
    m_a = a;
    m_mb = mb;
    m_mB = mB;
}
 
// for BLNP modell
EvtPFermi::EvtPFermi( const double& Lambda, const double& b )
{
    m_Lambda = Lambda;
    m_b = b;
}
 
//-----------
// Methods --
//-----------
 
double EvtPFermi::getFPFermi( const double& kplus )
{
    double FKplus;
    double x = kplus / ( m_mB - m_mb );
 
    if ( x >= 1 )
        return 0;
    if ( kplus <= -m_mb )
        return 0;
 
    FKplus = pow( 1 - x, m_a ) * exp( ( 1 + m_a ) * x );
 
    return FKplus;
}
 
// get value for the leading order exponential SF
double EvtPFermi::getSFBLNP( const double& what )
{
    double SF;
    double massB = 5.2792;
 
    if ( what > massB )
        return 0;
    if ( what < 0 )
        return 0;
 
#if defined( __SUNPRO_CC )
    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
        << "The tgamma function is not available on this platform\n";
    EvtGenReport( EVTGEN_ERROR, "EvtGen" )
        << "Presumably, you are getting the wrong answer, so I abort..";
    ::abort();
#else
    SF = pow( m_b, m_b ) / ( tgamma( m_b ) * m_Lambda ) *
         pow( what / m_Lambda, m_b - 1 ) * exp( -m_b * what / m_Lambda );
#endif
 
    return SF;
}