PDF/Main/Structure_Function.H

0001 #ifndef PDF_Main_Structure_Function_H
0002 #define PDF_Main_Structure_Function_H
0003
0004 #include "PDF/Main/ISR_Base.H"
0005 #include "PDF/Main/PDF_Base.H"
0006
0007 namespace PDF {
0008
0009   class Structure_Function : public ISR_Base {
0010   public:
0011
0012     // constructor
0013     Structure_Function(PDF::PDF_Base *_p_pdf,const ATOOLS::Flavour&);
0014
0015     // meber functions
0016     bool   CalculateWeight(double,double,double,double,int) override;
0017     double Weight(ATOOLS::Flavour) override;
0018
0019   };// end of class Structure_Function
0020
0021   /*!
0022     \file
0023     \brief contains the class PDF::Structure_Function.
0024   */
0025   /*!
0026     \class PDF::Structure_Function
0027     \brief This class is used for initial state radiation off particles characterized
0028            by energy fractions and scales of the hard interaction, i.e. structure functions
0029        and PDFs.
0030
0031     This class is used for treatment of initial state radiation through structure functions
0032     or PDFs that are consequently fully incorporated via a pointer to a suitable PDF_Base.
0033     It should be stressed here that for instance electromagnetic radiation off an electron
0034     is described through a structure function that is cast into the form of a PDF_Base.
0035     In any case, this treatment is clearly constrained to collinear initial state radiation.
0036
0037     The type related to this ISR_Base is "(SF)".
0038
0039     \param _p_pdf
0040     The pointer to the pdf for the structure function. It is handed over to the
0041     constructor, after having been instantiated by the PDF::PDF_Handler. Note that also
0042     structure functions like the one for the electron are handed over as PDF_Base.
0043   */
0044   /*!
0045     \var bool Structure_Function::CalculateWeight(double,double);
0046     After checking the ranges of the arguments, the energy fraction of the parton and
0047     the scale, this calculates the parton densities/weights for the structure function
0048     through a call to p_pdf->Calculate(x,q2). However the result of the pdf is not
0049     the parton density but \f$x\f$-times the parton density, therefore the actual internal
0050     weight is set to \f$1/x\f$ to be multiplied later on with the - eventuall flavour
0051     dependent - pdf piece.
0052   */
0053
0054 }// end of namespace PDF
0055
0056 #endif