PYTHIA  8.303
Classes | Public Member Functions | Protected Member Functions | List of all members
HadronLevel Class Reference

#include <HadronLevel.h>

Inheritance diagram for HadronLevel:


class  PriorityNode

Public Member Functions

 HadronLevel ()=default
bool init (TimeShowerPtr timesDecPtr, RHadrons *rHadronsPtrIn, DecayHandlerPtr decayHandlePtr, vector< int > handledParticles, StringIntPtr stringInteractionsPtrIn, PartonVertexPtr partonVertexPtrIn)
 Initialize HadronLevel classes as required. More...
StringFlavgetStringFlavPtr ()
 Get pointer to StringFlav instance (needed by BeamParticle).
bool next (Event &event)
 Generate the next event. More...
bool moreDecays (Event &event)
 Special routine to allow more decays if on/off switches changed. More...
bool initLowEnergyProcesses ()
 Prepare and pick process for a low-energy hadron-hadron scattering. More...
int pickLowEnergyProcess (int idA, int idB, double eCM, double mA, double mB)
 Pick process for a low-energy hadron-hadron scattering. More...
bool doLowEnergyProcess (int i1, int i2, int type, Event &event)
 Special routine to do a low-energy hadron-hadron scattering.
double getLowEnergySigma (int idA, int idB, double eCM, double mA, double mB, int type=0)
 Routine to allow user access to low-energy cross sections.
double getLowEnergySlope (int idA, int idB, double eCM, double mA, double mB, int type=2)
 Give access to b slope in elastic and diffractive interactions.
- Public Member Functions inherited from PhysicsBase
void initInfoPtr (Info &infoPtrIn)
 This function is called from above for physics objects used in a run. More...
virtual ~PhysicsBase ()
 Empty virtual destructor.
bool flag (string key) const
 Shorthand to read settings values.
int mode (string key) const
double parm (string key) const
string word (string key) const

Protected Member Functions

virtual void onInitInfoPtr () override
- Protected Member Functions inherited from PhysicsBase
 PhysicsBase ()
 Default constructor.
virtual void onBeginEvent ()
 This function is called in the very beginning of each Pythia::next call.
virtual void onEndEvent (Status)
virtual void onStat ()
 This function is called from the Pythia::stat() call.
void registerSubObject (PhysicsBase &pb)
 Register a sub object that should have its information in sync with this.

Additional Inherited Members

- Public Types inherited from PhysicsBase
enum  Status {
 Enumerate the different status codes the event generation can have.
- Protected Attributes inherited from PhysicsBase
InfoinfoPtr = {}
SettingssettingsPtr = {}
 Pointer to the settings database.
ParticleDataparticleDataPtr = {}
 Pointer to the particle data table.
HadronWidthshadronWidthsPtr = {}
 Pointer to the hadron widths data table.
RndmrndmPtr = {}
 Pointer to the random number generator.
CoupSMcoupSMPtr = {}
 Pointers to SM and SUSY couplings.
CoupSUSYcoupSUSYPtr = {}
BeamParticlebeamAPtr = {}
BeamParticlebeamBPtr = {}
BeamParticlebeamPomAPtr = {}
BeamParticlebeamPomBPtr = {}
BeamParticlebeamGamAPtr = {}
BeamParticlebeamGamBPtr = {}
BeamParticlebeamVMDAPtr = {}
BeamParticlebeamVMDBPtr = {}
PartonSystemspartonSystemsPtr = {}
 Pointer to information on subcollision parton locations.
SigmaTotalsigmaTotPtr = {}
 Pointer to the total/elastic/diffractive cross sections.
set< PhysicsBase * > subObjects
UserHooksPtr userHooksPtr

Detailed Description

The HadronLevel class contains the top-level routines to generate the transition from the partonic to the hadronic stage of an event.

Member Function Documentation

bool init ( TimeShowerPtr  timesDecPtr,
RHadrons rHadronsPtrIn,
DecayHandlerPtr  decayHandlePtr,
vector< int >  handledParticles,
StringIntPtr  stringInteractionsPtrIn,
PartonVertexPtr  partonVertexPtrIn 

Initialize HadronLevel classes as required.

Find settings. Initialize HadronLevel classes as required.

Store other input pointers.

Main flags.

Boundary mass between string and ministring handling.

For junction processing.

Allow R-hadron formation.

Particles that should decay or not before Bose-Einstein stage.

Displace hadron vertices from parton impact-parameter picture.

Need string density information be collected?

Initialize string interactions (Ropewalk and Flavour Ropes) if present.

Initialize auxiliary fragmentation classes.

Initialize auxiliary administrative class.

Initialize string and ministring fragmentation.

Initialize particle decays.

Initialize nucleon excitations.

Initialize low-energy framework.

Initialize low energy cross sections.

Initialize rescattering settings if applicable.

Break if conflicting settings.

Read settings for rescattering.

Initialize BoseEinstein.

Initialize DeuteronProduction.

Initialize Hidden-Valley fragmentation, if necessary.

Send flavour and z selection pointers to R-hadron machinery.

Initialize the colour tracing class.

Initialize the junction splitting class.


bool initLowEnergyProcesses ( )

Prepare and pick process for a low-energy hadron-hadron scattering.

Prepare to be able to pick a low-energy hadron-hadron scattering.

Prepare for low-energy QCD processes.

Return true if any process is switched on.

bool moreDecays ( Event event)

Special routine to allow more decays if on/off switches changed.

Allow more decays if on/off switches changed. Note: does not do sequential hadronization, e.g. for Upsilon.

Colour-octet onia states must be decayed to singlet + gluon.

Loop through all entries to find those that should decay.


bool next ( Event event)

Generate the next event.

Hadronize and decay the next parton-level.

Store current event size to mark Parton Level content.

Do Hidden-Valley fragmentation, if necessary.

Colour-octet onia states must be decayed to singlet + gluon.

Set lifetimes for already existing hadrons, like onia.

Remove junction structures.

Possibility of hadronization inside decay, but then no BE second time.

First part: string fragmentation.

Find the complete colour singlet configuration of the event. Keep junctions if we do shoving.

Fragment off R-hadrons, if necessary.

Save list with rapidity pairs of the different string pieces.

Let strings interact in rope hadronization treatment. Do the shoving treatment.

Extract all string segments from the event and do the string reulsion.

Find singlets again.

Prepare for flavour ropes.

Process all colour singlet (sub)systems.

Collect sequentially all partons in a colour singlet subsystem.

String fragmentation of each colour singlet (sub)system.

Low-mass string treated separately. Tell if diffractive system.

Displace hadron vertices transversely from parton MPI + shower.

Second part: sequential decays of short-lived particles (incl. K0).

If rescattering is off, we don't care about the order of the decays.

If rescattering is on, decays/rescatterings must happen in order.

Queue potential decays and rescatterings.

Get earliest decay/rescattering.

Skip if either particle has already interacted elsewhere.

Perform the queued action: decay.

If there is moreToDo, those things should also be handled in order?

Perform the queued action: two-body collision.

If multiple rescattering is on, check for new interactions.

If multiple rescattering is off, decay new hadrons.

Third part: include Bose-Einstein effects among current particles.

Fourth part: sequential decays also of long-lived particles.

Fifth part: deuteron production.

Normally done first time around, but sometimes not. (e.g. Upsilon decay can cause create unstable hadrons).


virtual void onInitInfoPtr ( )

If an object needs to set up infoPtr for sub objects, override this and call registerSubObject for each object in question.

Reimplemented from PhysicsBase.

int pickLowEnergyProcess ( int  idA,
int  idB,
double  eCM,
double  mA,
double  mB 

Pick process for a low-energy hadron-hadron scattering.

Chosen process.

If all processes are on, just call LowEnergySigma directly.

Trivial choice if only one process.

If only certain processes are on, calculate those cross sections.

Error if no processes has a positive cross section. Else pick process.

Pick specific resonance for proc == 9.


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