Page MenuHomeHEPForge
Files F10664307

No OneTemporary
Actions

View Options

diff --git a/PDF/HwRemDecayer.h b/PDF/HwRemDecayer.h
--- a/PDF/HwRemDecayer.h
+++ b/PDF/HwRemDecayer.h
@@ -1,582 +1,583 @@
// -*- C++ -*-
//
// HwRemDecayer.h is a part of Herwig++ - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2007 The Herwig Collaboration
//
// Herwig++ is licenced under version 2 of the GPL, see COPYING for details.
// Please respect the MCnet academic guidelines, see GUIDELINES for details.
//
#ifndef HERWIG_HwRemDecayer_H
#define HERWIG_HwRemDecayer_H
//
// This is the declaration of the HwRemDecayer class.
//
#include "ThePEG/PDT/RemnantDecayer.h"
#include "ThePEG/Handlers/EventHandler.h"
#include "ThePEG/Repository/EventGenerator.h"
#include "ThePEG/EventRecord/SubProcess.h"
#include "ThePEG/PDF/BeamParticleData.h"
#include "Herwig++/Shower/Couplings/ShowerAlpha.h"
#include "Herwig++/PDT/StandardMatchers.h"
#include "ThePEG/PDT/StandardMatchers.h"
#include "HwRemDecayer.fh"
namespace Herwig {
using namespace ThePEG;
/**
* The HwRemDecayer class is responsible for the decay of the remnants. Additional
* secondary scatters have to be evolved backwards to a gluon, the
* first/hard interaction has to be evolved back to a valence quark.
* This is all generated inside this class,
* which main methods are then called by the ShowerHandler.
*
* A simple forced splitting algorithm is used.
* This takes the Remnant object produced from the PDF and backward
* evolution (hadron - parton) and produce partons with the remaining
* flavours and with the correct colour connections.
*
* The algorithim operates by starting with the parton which enters the hard process.
* If this is from the sea there is a forced branching to produce the antiparticle
* from a gluon branching. If the parton entering the hard process was a gluon, or
* a gluon was produced from the first step of the algorithm, there is then a further
* branching back to a valence parton. After these partons have been produced a quark or
* diquark is produced to give the remaining valence content of the incoming hadron.
*
* The forced branching are generated using a scale between QSpac and EmissionRange times
* the minimum scale. The energy fractions are then distributed using
* \f[\frac{\alpha_S}{2\pi}\frac{P(z)}{z}f(x/z,\tilde{q})\f]
* with the massless splitting functions.
*
* \author Manuel B\"ahr
*
* @see \ref HwRemDecayerInterfaces "The interfaces"
* defined for HwRemDecayer.
*/
class HwRemDecayer: public RemnantDecayer {
public:
/** Typedef to store information about colour partners */
typedef vector<pair<tPPtr, tPPtr> > PartnerMap;
public:
/**
* The default constructor.
*/
inline HwRemDecayer() : ptmin_(-1.*GeV), maxtrySoft_(10),
colourDisrupt_(1.0),
_kinCutoff(0.75*GeV),
_forcedSplitScale(2.5*GeV),
_range(1.1), _zbin(0.05),_ybin(0.),
_nbinmax(100), DISRemnantOpt_(0),
pomeronStructure_(0) {}
/** @name Virtual functions required by the Decayer class. */
//@{
/**
* Check if this decayer can perfom the decay specified by the
* given decay mode.
* @return true if this decayer can handle the given mode, otherwise false.
*/
virtual bool accept(const DecayMode &) const {
return true;
}
/**
* Return true if this decayer can handle the extraction of the \a
* extracted parton from the given \a particle.
*/
virtual bool canHandle(tcPDPtr particle, tcPDPtr parton) const;
/**
* Return true if this decayed can extract more than one parton from
* a particle.
*/
virtual bool multiCapable() const {
return true;
}
/**
* Perform a decay for a given DecayMode and a given Particle instance.
* @param dm the DecayMode describing the decay.
* @param p the Particle instance to be decayed.
* @param step the step we are working on.
* @return a ParticleVector containing the decay products.
*/
virtual ParticleVector decay(const DecayMode & dm, const Particle & p, Step & step) const;
//@}
public:
/**
* struct that is used to catch exceptions which are thrown
* due to energy conservation issues of additional soft scatters
*/
struct ExtraSoftScatterVeto {};
/** @name Functions used by the persistent I/O system. */
//@{
/**
* Function used to write out object persistently.
* @param os the persistent output stream written to.
*/
void persistentOutput(PersistentOStream & os) const;
/**
* Function used to read in object persistently.
* @param is the persistent input stream read from.
* @param version the version number of the object when written.
*/
void persistentInput(PersistentIStream & is, int version);
//@}
/**
* The standard Init function used to initialize the interfaces.
* Called exactly once for each class by the class description system
* before the main function starts or
* when this class is dynamically loaded.
*/
static void Init();
/**
* Do several checks and initialization, for remnantdecay inside ShowerHandler.
*/
void initialize(pair<tRemPPtr, tRemPPtr> rems, tPPair beam, Step & step,
Energy forcedSplitScale);
/**
* Initialize the soft scattering machinery.
* @param ptmin = the pt cutoff used in the UE model
* @param beta = slope of the soft pt-spectrum
*/
void initSoftInteractions(Energy ptmin, InvEnergy2 beta);
/**
* Perform the acual forced splitting.
* @param partons is a pair of ThePEG::Particle pointers which store the final
* partons on which the shower ends.
* @param pdfs are pointers to the pdf objects for both beams
* @param first is a flage wether or not this is the first or a secondary interation
*/
void doSplit(pair<tPPtr, tPPtr> partons, pair<tcPDFPtr, tcPDFPtr> pdfs, bool first);
/**
* Perform the final creation of the diquarks. Set the remnant masses and do
* all colour connections.
* @param colourDisrupt = variable to control how many "hard" scatters
* are colour isolated
* @param softInt = parameter for the number of soft scatters
*/
void finalize(double colourDisrupt=0.0, unsigned int softInt=0);
/**
* Find the children
*/
void findChildren(tPPtr,vector<PPtr> &) const;
protected:
/** @name Clone Methods. */
//@{
/**
* Make a simple clone of this object.
* @return a pointer to the new object.
*/
virtual IBPtr clone() const {return new_ptr(*this);}
/** Make a clone of this object, possibly modifying the cloned object
* to make it sane.
* @return a pointer to the new object.
*/
virtual IBPtr fullclone() const {return new_ptr(*this);}
//@}
protected:
/** @name Standard Interfaced functions. */
//@{
/**
* Initialize this object after the setup phase before saving an
* EventGenerator to disk.
* @throws InitException if object could not be initialized properly.
*/
virtual void doinit() {
Interfaced::doinit();
_ybin=0.25/_zbin;
}
//@}
private:
/**
* The static object used to initialize the description of this class.
* Indicates that this is a concrete class with persistent data.
*/
static ClassDescription<HwRemDecayer> initHwRemDecayer;
/**
* The assignment operator is private and must never be called.
* In fact, it should not even be implemented.
*/
HwRemDecayer & operator=(const HwRemDecayer &);
private:
/**
* Simple struct to store info about baryon quark and di-quark
* constituents.
*/
struct HadronContent {
/**
* manually extract the valence flavour \a id.
*/
inline void extract(int id) {
for(unsigned int i=0; i<flav.size(); i++) {
if(id == sign*flav[i]){
if(hadron->id() == ParticleID::gamma ||
- (hadron->id() == ParticleID::pomeron && pomeronStructure==1)) {
+ (hadron->id() == ParticleID::pomeron && pomeronStructure==1) ||
+ hadron->id() == ParticleID::reggeon) {
flav[0] = id;
flav[1] = -id;
extracted = 0;
flav.resize(2);
}
else if (hadron->id() == ParticleID::pomeron && pomeronStructure==0) {
extracted = 0;
}
else {
extracted = i;
}
break;
}
}
}
/**
* Return a proper particle ID assuming that \a id has been removed
* from the hadron.
*/
long RemID() const;
/**
* Method to determine whether \a parton is a quark from the sea.
* @return TRUE if \a parton is neither a valence quark nor a gluon.
*/
bool isSeaQuark(tcPPtr parton) const {
return ((parton->id() != ParticleID::g) && ( !isValenceQuark(parton) ) );
}
/**
* Method to determine whether \a parton is a valence quark.
*/
bool isValenceQuark(tcPPtr parton) const {
return isValenceQuark(parton->id());
}
/**
* Method to determine whether \a parton is a valence quark.
*/
bool isValenceQuark(int id) const {
return find(flav.begin(),flav.end(),sign*id) != flav.end();
}
/** The valence flavours of the corresponding baryon. */
vector<int> flav;
/** The array index of the extracted particle. */
int extracted;
/** -1 if the particle is an anti-particle. +1 otherwise. */
int sign;
/** The ParticleData objects of the hadron */
tcPDPtr hadron;
/** Pomeron treatment */
unsigned int pomeronStructure;
};
/**
* Return a HadronContent struct from a PPtr to a hadron.
*/
HadronContent getHadronContent(tcPPtr hadron) const;
/**
* Do the forced Splitting of the Remnant with respect to the
* extracted parton \a parton.
* @param parton = PPtr to the parton going into the subprocess.
* @param content = HadronContent struct to keep track of flavours.
* @param rem = Pointer to the ThePEG::RemnantParticle.
* @param used = Momentum vector to keep track of remaining momenta.
* @param partners = Vector of pairs filled with tPPtr to the particles
* which should be colour connected.
* @param pdf pointer to the PDF Object which is used for this particle
* @param first = Flag for the first interaction.
*/
void split(tPPtr parton, HadronContent & content, tRemPPtr rem,
Lorentz5Momentum & used, PartnerMap & partners, tcPDFPtr pdf, bool first);
/**
* Merge the colour lines of two particles
* @param p1 = Pointer to particle 1
* @param p2 = Pointer to particle 2
* @param anti = flag to indicate, if (anti)colour was extracted as first parton.
*/
void mergeColour(tPPtr p1, tPPtr p2, bool anti) const;
/**
* Set the colour connections.
* @param partners = Object that holds the information which particles to connect.
* @param anti = flag to indicate, if (anti)colour was extracted as first parton.
* @param disrupt parameter for disruption of the colour structure
*/
void fixColours(PartnerMap partners, bool anti, double disrupt) const;
/**
* Set the momenta of the Remnants properly and boost the decay particles.
*/
void setRemMasses() const;
/**
* This creates a parton from the remaining flavours of the hadron. The
* last parton used was a valance parton, so only 2 (or 1, if meson) flavours
* remain to be used.
*/
PPtr finalSplit(const tRemPPtr rem, long remID,
Lorentz5Momentum usedMomentum) const {
// Create the remnant and set its momentum, also reset all of the decay
// products from the hadron
PPtr remnant = new_ptr(Particle(getParticleData(remID)));
Lorentz5Momentum prem(rem->momentum()-usedMomentum);
prem.setMass(getParticleData(remID)->constituentMass());
prem.rescaleEnergy();
remnant->set5Momentum(prem);
// Add the remnant to the step, but don't do colour connections
thestep->addDecayProduct(rem,remnant,false);
return remnant;
}
/**
* This takes the particle and find a splitting for np -> p + child and
* creates the correct kinematics and connects for such a split. This
* Splitting has an upper bound on qtilde given by the energy argument
* @param rem The Remnant
* @param child The PDG code for the outgoing particle
* @param oldQ The maximum scale for the evolution
* @param oldx The fraction of the hadron's momentum carried by the last parton
* @param pf The momentum of the last parton at input and after branching at output
* @param p The total emitted momentum
* @param content The content of the hadron
*/
PPtr forceSplit(const tRemPPtr rem, long child, Energy &oldQ, double &oldx,
Lorentz5Momentum &pf, Lorentz5Momentum &p,
HadronContent & content) const;
/** @name Soft interaction methods. */
//@{
/**
* Produce pt values according to dN/dp_T = N p_T exp(-beta_*p_T^2)
*/
Energy softPt() const;
/**
* Get the 2 pairs of 5Momenta for the scattering. Needs calling of
* initSoftInteractions.
*/
void softKinematics(Lorentz5Momentum &r1, Lorentz5Momentum &r2,
Lorentz5Momentum &g1, Lorentz5Momentum &g2) const;
/**
* Create N soft gluon interactions
*/
void doSoftInteractions(unsigned int N);
/**
* Method to add a particle to the step
* @param parent = pointer to the parent particle
* @param id = Particle ID of the newly created particle
* @param p = Lorentz5Momentum of the new particle
*/
tPPtr addParticle(tcPPtr parent, long id, Lorentz5Momentum p) const;
//@}
/**
* A flag which indicates, whether the extracted valence quark was a
* anti particle.
*/
pair<bool, bool> theanti;
/**
* variable to sum up the x values of the extracted particles
*/
pair<double, double> theX;
/**Pair of HadronContent structs to know about the quark content of the beams*/
pair<HadronContent, HadronContent> theContent;
/**Pair of Lorentz5Momentum to keep track of the forced splitting product momenta*/
pair<Lorentz5Momentum, Lorentz5Momentum> theUsed;
/**
* Pair of PartnerMap's to store the particles, which will be colour
* connected in the end.
*/
pair<PartnerMap, PartnerMap> theMaps;
/**
* Variable to hold a pointer to the current step. The variable is used to
* determine, wether decay(const DecayMode & dm, const Particle & p, Step & step)
* has been called in this event or not.
*/
StepPtr thestep;
/**
* Pair of Remnant pointers. This is needed to boost
* in the Remnant-Remnant CMF after all have been decayed.
*/
pair<RemPPtr, RemPPtr> theRems;
/**
* The beam particle data for the current incoming hadron
*/
mutable tcPPtr theBeam;
/**
* the beam data
*/
mutable Ptr<BeamParticleData>::const_pointer theBeamData;
/**
* The PDF for the current initial-state shower
*/
mutable tcPDFPtr _pdf;
private:
/** @name Soft interaction variables. */
//@{
/**
* Pair of soft Remnant pointers, i.e. Diquarks.
*/
tPPair softRems_;
/**
* ptcut of the UE model
*/
Energy ptmin_;
/**
* slope of the soft pt-spectrum: dN/dp_T = N p_T exp(-beta*p_T^2)
*/
InvEnergy2 beta_;
/**
* Maximum number of attempts for the regeneration of an additional
* soft scattering, before the number of scatters is reduced.
*/
unsigned int maxtrySoft_;
/**
* Variable to store the relative number of colour disrupted
* connections to additional soft subprocesses.
*/
double colourDisrupt_;
//@}
/** @name Forced splitting variables. */
//@{
/**
* The kinematic cut-off
*/
Energy _kinCutoff;
/**
* The PDF freezing scale as set in ShowerHandler
*/
Energy _forcedSplitScale;
/**
* Range for emission
*/
double _range;
/**
* Size of the bins in z for the interpolation
*/
double _zbin;
/**
* Size of the bins in y for the interpolation
*/
double _ybin;
/**
* Maximum number of bins for the z interpolation
*/
int _nbinmax;
/**
* Pointer to the object calculating the QCD coupling
*/
ShowerAlphaPtr _alpha;
/**
* Option for the DIS remnant
*/
unsigned int DISRemnantOpt_;
/**
* Option for the treatment of the pomeron structure
*/
unsigned int pomeronStructure_;
//@}
};
}
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/** This template specialization informs ThePEG about the
* base classes of HwRemDecayer. */
template <>
struct BaseClassTrait<Herwig::HwRemDecayer,1> {
/** Typedef of the first base class of HwRemDecayer. */
typedef RemnantDecayer NthBase;
};
/** This template specialization informs ThePEG about the name of
* the HwRemDecayer class and the shared object where it is defined. */
template <>
struct ClassTraits<Herwig::HwRemDecayer>
: public ClassTraitsBase<Herwig::HwRemDecayer> {
/** Return a platform-independent class name */
static string className() { return "Herwig::HwRemDecayer"; }
/**
* The name of a file containing the dynamic library where the class
* HwRemDecayer is implemented. It may also include several, space-separated,
* libraries if the class HwRemDecayer depends on other classes (base classes
* excepted). In this case the listed libraries will be dynamically
* linked in the order they are specified.
*/
static string library() { return "HwShower.so"; }
};
/** @endcond */
}
#endif /* HERWIG_HwRemDecayer_H */

File Metadata

Mime Type
text/x-diff
Expires
Thu, Apr 24, 6:36 AM (1 d, 16 h)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
4887763
Default Alt Text
(17 KB)

Event Timeline