#include <HepMC2.h>

Inheritance diagram for Pythia8ToHepMC:

Public Member Functions
	Pythia8ToHepMC ()
	Constructor and destructor.

bool	fill_next_event (Pythia8::Pythia &pythia, GenEvent &evt, int ievnum=-1, bool append=false, GenParticle *rootParticle=0, int iBarcode=-1)
	The recommended method to convert Pythia events into HepMC ones.

bool	fill_next_event (Pythia8::Pythia &pythia, GenEvent evt, int ievnum=-1, bool append=false, GenParticle rootParticle=0, int iBarcode=-1)

bool	fill_next_event (Pythia8::Event &pyev, GenEvent &evt, int ievnum=-1, const Pythia8::Info pyinfo=0, Pythia8::Settings pyset=0, bool append=false, GenParticle *rootParticle=0, int iBarcode=-1)
	Alternative method to convert Pythia events into HepMC ones.

bool	fill_next_event (Pythia8::Event &pyev, GenEvent evt, int ievnum=-1, const Pythia8::Info pyinfo=0, Pythia8::Settings pyset=0, bool append=false, GenParticle rootParticle=0, int iBarcode=-1)

bool	print_inconsistency () const
	Read out values for some switches.

bool	free_parton_exception () const

bool	free_parton_warnings () const

bool	convert_gluon_to_0 () const

bool	store_pdf () const

bool	store_proc () const

bool	store_xsec () const

bool	store_weights () const

void	set_print_inconsistency (bool b=true)
	Set values for some switches.

void	set_free_parton_exception (bool b=true)

void	set_free_parton_warnings (bool b=true)

void	set_convert_gluon_to_0 (bool b=false)

void	set_store_pdf (bool b=true)

void	set_store_proc (bool b=true)

void	set_store_xsec (bool b=true)

void	set_store_weights (bool b=true)

Detailed Description

The Pythia8ToHepMC class.

Member Function Documentation

bool fill_next_event	(	Pythia8::Event &	pyev,
		GenEvent *	evt,
		int	ievnum = `-1`,
		const Pythia8::Info *	pyinfo = `0`,
		Pythia8::Settings *	pyset = `0`,
		bool	append = `false`,
		GenParticle *	rootParticle = `0`,
		int	iBarcode = `-1`
	)

inline

Main method for conversion from PYTHIA event to HepMC event. Read one event from Pythia8 and fill a new GenEvent, alternatively append to an existing GenEvent, and return T/F = success/failure.

Error if no event passed.

Update event number counter.

Conversion factors from Pythia units GeV and mm to HepMC ones.

Set up for alternative to append to an existing event.

New vertex associated with appended particles.

1a. If there is a HIInfo object fill info from that.

Create a particle instance for each entry and fill a map, and a vector which maps from the particle index to the GenParticle address.

Fill the particle.

Colour flow uses index 1 and 2.

Here we assume that the first two particles in the list are the incoming beam particles.

Loop over particles AGAIN, this time creating vertices. We build the production vertex for each entry in hepevt. The HEPEVT pointers are bi-directional, so gives decay vertices as well.

3a. Search to see if a production vertex already exists.

note that in Pythia8 there is a particle number 0!

3b. If no suitable production vertex exists - and the particle has at least one mother or position information to store - make one.

3c. If prod_vtx doesn't already have position specified, fill it.

3d. loop over mothers to make sure their end_vertices are consistent.

If end vertex of the mother isn't specified, do it now.

Problem scenario: the mother already has a decay vertex which differs from the daughter's production vertex. Can happen with Vincia showers since antenna emissions have two parents. In that case, let vertex structure be defined by first parent, ignoring second parent.

Otherwise this means there is internal inconsistency in the HEPEVT event record. Print an error. Note: we could provide a fix by joining the two vertices with a dummy particle if the problem arises often.

End of vertex-setting loops.

If hadronization switched on then no final coloured particles.

Check for particles which come from nowhere, i.e. are without mothers or daughters. These need to be attached to a vertex, or else they will never become part of the event.

Also check for free partons (= gluons and quarks; not diquarks?).

Done if only appending to already existing event.

Store PDF, weight, cross section and other event information. Flavours of incoming partons.

Store PDF information.

Store process code, scale, alpha_em, alpha_s.

Store cross-section information in pb and event weight. The latter is usually dimensionless, but in units of pb for Les Houches strategies +-4.

If multiweights with possibly different xsec, overwrite central value

Done for new event.

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

include/Pythia8Plugins/HepMC2.h

Public Member Functions

Detailed Description

Member Function Documentation