PYTHIA  8.303
Public Member Functions | List of all members
EPAexternal Class Reference

Equivalent photon approximation for sampling with external photon flux. More...

#include <PartonDistributions.h>

Inheritance diagram for EPAexternal:
PDF

Public Member Functions

 EPAexternal (int idBeamIn, double m2In, PDFPtr gammaFluxPtrIn, PDFPtr gammaPDFPtrIn, Info *infoPtrIn)
 Constructor.
 
void xfUpdate (int, double x, double Q2)
 Update PDFs. More...
 
double xfFlux (int id, double x, double Q2=1.)
 External flux and photon PDFs, and approximated flux for sampling. More...
 
double xfGamma (int id, double x, double Q2)
 Photon PDFs used for the convolution with the flux. More...
 
double xfApprox (int id, double x, double Q2)
 The approximated photon flux x*f^{gamma}(x,Q2). More...
 
double intFluxApprox ()
 
bool hasApproxGammaFlux ()
 This derived class use approximated flux for sampling.
 
double getXmin ()
 Kinematics.
 
double getXhadr ()
 
double sampleXgamma (double xMinIn)
 Sampling of the x and Q2 according to differential flux. More...
 
double sampleQ2gamma (double)
 
- Public Member Functions inherited from PDF
 PDF (int idBeamIn=2212)
 Constructor.
 
virtual ~PDF ()
 Destructor.
 
virtual bool isSetup ()
 Confirm that PDF has been set up (important for LHAPDF and H1 Pomeron).
 
virtual void newValenceContent (int idVal1In, int idVal2In)
 Dynamic choice of meson valence flavours for pi0, K0S, K0L, Pomeron.
 
virtual void setExtrapolate (bool)
 Allow extrapolation beyond boundaries. This is optional.
 
virtual double xf (int id, double x, double Q2)
 Read out parton density. More...
 
virtual double xfVal (int id, double x, double Q2)
 Read out valence and sea part of parton densities. More...
 
virtual double xfSea (int id, double x, double Q2)
 Only sea part of parton densities. More...
 
virtual bool insideBounds (double, double)
 Check whether x and Q2 values fall inside the fit bounds (LHAPDF6 only).
 
virtual double alphaS (double)
 Access the running alpha_s of a PDF set (LHAPDF6 only).
 
virtual double mQuarkPDF (int)
 Return quark masses used in the PDF fit (LHAPDF6 only).
 
virtual int nMembers ()
 Return number of members of this PDF family (LHAPDF6 only).
 
virtual void calcPDFEnvelope (int, double, double, int)
 Calculate PDF envelope.
 
virtual void calcPDFEnvelope (pair< int, int >, pair< double, double >, double, int)
 
virtual PDFEnvelope getPDFEnvelope ()
 
virtual double gammaPDFxDependence (int, double)
 Approximate photon PDFs by decoupling the scale and x-dependence.
 
virtual double gammaPDFRefScale (int)
 Provide the reference scale for logarithmic Q^2 evolution for photons.
 
virtual int sampleGammaValFlavor (double)
 Sample the valence content for photons.
 
virtual double xfIntegratedTotal (double)
 The total x-integrated PDFs. Relevant for MPIs with photon beams.
 
virtual double xGamma ()
 Return the sampled value for x_gamma.
 
virtual void xPom (double=-1.0)
 Keep track of pomeron momentum fraction.
 
virtual double xfMax (int id, double x, double Q2)
 Normal PDFs unless gamma inside lepton -> an overestimate for sampling.
 
virtual double xfSame (int id, double x, double Q2)
 Normal PDFs unless gamma inside lepton -> Do not sample x_gamma.
 
virtual void setVMDscale (double=1.)
 Allow for new scaling factor for VMD PDFs.
 

Additional Inherited Members

- Protected Member Functions inherited from PDF
void setValenceContent ()
 Resolve valence content for assumed meson. Possibly modified later. More...
 
void printErr (string errMsg, Info *infoPtr=0)
 Small routine for error printout, depending on infoPtr existing or not.
 
- Protected Attributes inherited from PDF
int idBeam
 Store relevant quantities.
 
int idBeamAbs
 
int idSav
 
int idVal1
 
int idVal2
 
double xSav
 
double Q2Sav
 
double xu
 
double xd
 
double xs
 
double xubar
 
double xdbar
 
double xsbar
 
double xc
 
double xb
 
double xg
 
double xlepton
 
double xgamma
 
double xuVal
 
double xuSea
 
double xdVal
 
double xdSea
 
bool isSet
 
bool isInit
 
double xsVal
 More valence and sea flavors for photon PDFs.
 
double xcVal
 
double xbVal
 
double xsSea
 
double xcSea
 
double xbSea
 
bool hasGammaInLepton
 True if a photon beam inside a lepton beam, otherwise set false.
 

Detailed Description

Equivalent photon approximation for sampling with external photon flux.

Member Function Documentation

double intFluxApprox ( )
virtual

Return integrated over-estimate for photon flux to approximate soft cross sections.

Check the used approximation and return the integral.

Reimplemented from PDF.

double sampleXgamma ( double  xMinIn)
virtual

Sampling of the x and Q2 according to differential flux.

Sample the x_gamma value according to given photon flux approximation.

Sample with lepton-type flux.

Sample with photon flux for nuclei.

Calculate the integrals of over estimates.

Select the sampling region.

Sample x.

Return zero for undefined cases.

Reimplemented from PDF.

double xfApprox ( int  id,
double  x,
double  Q2 
)
virtual

The approximated photon flux x*f^{gamma}(x,Q2).

Differential in Q2 for leptons.

Piece-wise approximation for heavy ions.

Reimplemented from PDF.

double xfFlux ( int  id,
double  x,
double  Q2 = 1. 
)
virtual

External flux and photon PDFs, and approximated flux for sampling.

Accurate flux, provided externally.

The external flux, check that pointer exists.

Reimplemented from PDF.

double xfGamma ( int  id,
double  x,
double  Q2 
)
virtual

Photon PDFs used for the convolution with the flux.

Return xf from the photon PDF.

Reimplemented from PDF.

void xfUpdate ( int  ,
double  x,
double  Q2 
)
virtual

Update PDFs.

Approximate the differential photon flux with alphaEM/PI/x/Q2. Derived from EPA for leptons but provides leading (small-x) behaviour for hadrons as well.

Calculate (Q2-integrated) approximation for xfGamma.

Integrated in Q2, to be used for direct process sampling.

Approximate the convolution with photon PDFs.

To preserve x/xGamma < 1.

Integrals for the overestimates.

Multiply the approximated flux with PDFs.

idSav = 9 to indicate that all flavours reset.

Implements PDF.


The documentation for this class was generated from the following files: