PYTHIA  8.303
Public Member Functions | List of all members
Lepton2gamma Class Reference

#include <PartonDistributions.h>

Inheritance diagram for Lepton2gamma:

Public Member Functions

 Lepton2gamma (int idBeamIn, double m2leptonIn, double Q2maxGamma, PDFPtr gammaPDFPtrIn, Info *infoPtrIn)
void xfUpdate (int id, double x, double Q2)
 Overload the member function definitions where relevant. More...
double xGamma ()
 Return the sampled value for x_gamma.
double xfMax (int id, double x, double Q2)
double xfSame (int id, double x, double Q2)
double sampleQ2gamma (double Q2min)
 Sample the Q2 value.
- Public Member Functions inherited from PDF
 PDF (int idBeamIn=2212)
virtual ~PDF ()
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 void xPom (double=-1.0)
 Keep track of pomeron momentum fraction.
virtual double xfFlux (int, double, double)
 Return accurate and approximated photon fluxes and PDFs.
virtual double xfApprox (int, double, double)
virtual double xfGamma (int, double, double)
virtual double intFluxApprox ()
virtual bool hasApproxGammaFlux ()
virtual double getXmin ()
 Return the kinematical limits and sample Q2 and x.
virtual double getXhadr ()
virtual double sampleXgamma (double)
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

Convolution with photon flux from leptons and photon PDFs. Photon flux from equivalent photon approximation (EPA). Contains a pointer to a photon PDF set and samples the convolution integral event-by-event basis. Includes also a overestimate for the PDF set in order to set up the phase-space sampling correctly.

Member Function Documentation

double xfMax ( int  id,
double  x,
double  Q2 

Approximate the maximum of convoluted PDF to correctly set up the sampling of the phase space.

Find the maximum x value at given Q2max and sqrt(s).

Set PDFs to zero outside allowed x values.

Pre-calculate some logs.

Find approximate x-behaviour for each flavour. Optimized for CJKL.

Direct photons in usual lepton PDFs.

Return the approximation.

Reimplemented from PDF.

double xfSame ( int  id,
double  x,
double  Q2 

Return PDF without sampling x_gamma values to compute cross section with rescaled sHat. Not very elegant but no need to modify the xfUpdate call.

Reimplemented from PDF.

void xfUpdate ( int  id,
double  x,
double  Q2 

Overload the member function definitions where relevant.

Update PDFs and sample a value for x_gamma.

Find the maximum x value at given Q2max and sqrt(s).

If outside allowed x values set PDFs to zero.

Pre-calculate some logs.

Sample x_gamma.

Evaluate the PDFs at x/x_gamma.

Calculate the Q^2_min for sampled x_gamma.

Correct with weight.

Calculate the PDF value.

Photon inside electron not currently implemented (Use point-like lepton).

idSav = 9 to indicate that all flavours reset.

Implements PDF.

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