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diff --git a/Hadronization/Cluster.h b/Hadronization/Cluster.h
--- a/Hadronization/Cluster.h
+++ b/Hadronization/Cluster.h
@@ -1,326 +1,331 @@
// -*- C++ -*-
//
// Cluster.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_Cluster_H
#define HERWIG_Cluster_H
#include <ThePEG/Pointer/Ptr.h>
#include <ThePEG/Pointer/PtrTraits.h>
#include <ThePEG/Pointer/RCPtr.h>
#include <ThePEG/EventRecord/Particle.h>
#include "Herwig++/Utilities/EnumParticles.h"
#include <iostream>
#include "CluHadConfig.h"
#include "ClusterHadronizationHandler.fh"
#include "Cluster.fh"
namespace Herwig {
using namespace ThePEG;
/** \ingroup Hadronization
* \class Cluster
* \brief This class describes a cluster object.
* \author Philip Stephens
* \author Alberto Ribon
*
* This class represents a cluster, which is a colour singlet made usually
* of two components (quark-antiquark, quark-diquark, antiquark-antidiquark)
* or rarely by three components (quark-quark-quark, antiquark-antiquark-
* antiquark). A reference to the container with the pointers to its
* Components is provided.
*
* The class provides access to the pointers which point to:
*
* - The cluster parent. In the case that the cluster it is a fission
* product of a heavy cluster the parent is a cluster. If the cluster
* is formed from the perturbative partons then the parents will be
* the colour connected partons that formed the cluster.
* - The children (usually two). In the case the cluster is a
* heavy cluster that undergoes fission the children are clusters.
* Occasionally the cluster has been "redefined" (re-interpreted). For
* example in the case that three quark or anti-quark components
* have been redefined as two components (quark+diquark, or antiquark+
* antidiquark).
* - The (eventual) reshuffling partner, necessary for energy-momentum
* conservation when light clusters are decayed into single hadron. Not
* all clusters will have a reshuffling partner.
*
* Notice that in order to determine the cluster position from the positions
* of the components, the Cluster class needs some parameters.
* Because the Cluster class is neither interfaced nor persistent,
* a static pointer to the ClusterHadronizationHandler class instance,
* where the parameters are, is used. This static pointer is
* set via the method setPointerClusterHadHandler(), during the
* run initialization, doinitrun() of ClusterHadronizationHandler.
*
* @see ClusterHadronizationHandler
*/
class Cluster : public Particle {
public:
+
+ /**
+ * ColourReconnector needs access to the _original constituents.
+ */
+ friend class ColourReconnector;
/** @name Standard constructors and destructors. */
//@{
/**
* Default constructor.
*/
Cluster();
/**
* Constructor with a particleData pointer
*/
Cluster(tcEventPDPtr);
/**
* This creates a cluster from 2 (or 3) partons.
*/
Cluster(tPPtr part1, tPPtr part2, tPPtr part3 = tPPtr());
/**
* Also a constructor where a particle is given not a cluster.
*/
Cluster(const Particle &);
//@}
/**
* Set the static pointer to the ClusterHadronizationHandler object.
* The pointer is set in ClusterHadronizationHandler::doinitrun().
*/
static void setPointerClusterHadHandler(tcCluHadHdlPtr gp);
/**
* Number of quark (diquark) constituents (normally two).
*/
inline int numComponents() const;
/**
* Sum of the constituent masses of the components of the cluster.
*/
Energy sumConstituentMasses() const;
/**
* Set cluster mass.
*/
inline void setMass(const Energy inputMass);
/**
* Returns the ith constituent.
*/
tPPtr particle(int i) const;
/**
* Returns whether the ith constituent is from a perturbative process.
*/
bool isPerturbative(int) const;
/**
* Sets whether the ith constituent is from a perturbative process.
*/
void setPerturbative(int,bool);
/**
* Indicates whether the ith constituent is a beam remnant.
*/
bool isBeamRemnant(int) const;
/**
* Sets whether the ith constituent is a beam remnant.
*/
void setBeamRemnant(int,bool);
/**
* Returns the clusters id, not the same as the PDG id.
*/
int clusterId() const { return _id; }
public:
/**
* Returns the cluster that was used for reshuffling.
*/
inline tClusterPtr reshufflingPartnerCluster() const;
/**
* Set the pointer to the reshuffling partner cluster.
*/
inline void reshufflingPartnerCluster(const tClusterPtr inputCluPtr);
/**
* Returns true when a constituent is a beam remnant.
*/
bool isBeamCluster() const;
/**
* Sets the component (if any) that points to "part" as a beam remnant.
*/
void isBeamCluster(tPPtr part);
/**
* Returns true if this cluster is to be handled by the hadronization.
*/
bool isAvailable() const;
/**
* Sets the value of availability.
*/
void isAvailable(bool inputAvailable);
/**
* Return true if the cluster does not have cluster parent.
*/
inline bool isStatusInitial() const;
/**
* Return true if the cluster does not have cluster children and
* it is not already decayed (i.e. it does not have hadron children)
* (to be used only after the fission of heavy clusters).
*/
inline bool isReadyToDecay() const;
/**
* Return true if the cluster has one and only one cluster children
* and no hadron children: that means either that its three quarks or
* anti-quarks components have been redefined as two components
* (quark+diquark, or antiquark+antidiquark), or that the cluster
* has been used as a partner for the momentum reshuffling necessary
* to conserve energy-momentum when a light cluster is decayed into
* a single hadron (notice that this latter light cluster has
* isRedefined() false, because it has an hadron child).
* In both cases, the unique cluster children is the new redefined
* cluster. The two cases can be distinguish by the next method.
*/
inline bool isRedefined() const;
/**
* Return true when it has a reshuffling partner.
* Notice that a cluster can have hasBeenReshuffled() true but
* isRedefined() false: this is the case of a light cluster
* that decays into a single hadron.
*/
inline bool hasBeenReshuffled() const;
/**
* Return true if the cluster has hadron children.
*/
bool isStatusFinal() const;
protected:
/** @name Clone Methods. */
//@{
/**
* Make a simple clone of this object.
* @return a pointer to the new object.
*/
inline virtual PPtr clone() const;
/** Make a clone of this object, possibly modifying the cloned object
* to make it sane.
* @return a pointer to the new object.
*/
inline virtual PPtr fullclone() const;
//@}
private:
/**
* Private and non-existent assignment operator.
*/
Cluster & operator=(const Cluster &);
/**
* Calculate the 5-momentum vector of the cluster
* The 5-momentum of the cluster is given by
* \f[ P = \sum_i p_i \f]
* and the mass of the cluster is \f$m^2 = P^2\f$
*/
void calculateP();
/**
* Calculate the 4-position vector of the cluster
* Displacement of the ith constituent given by momentum \f$p_i\f$
* vertex \f$x_i\f$ and mass \f$m_i\f$ is
* \f[ D_i = -C \log(r) \frac{p_i}{\sqrt{(p_i^2 - m_i^2)^2 + v^4}} \f]
* where \f$r\f$ is a random number [0,1],
* \f$v\f$ is the minimum virtuality and \f$C\f$ is
* a conversion factor from GeV to millimeters. We can then find the
* difference in \f$s\f$ factors as
* \f[ (s_1-s_2) = \frac{(\vec{p}_1 + \vec{p}_2) \cdot (\vec{x}_2 -
* \vec{x}_1)}{(\vec{p}_1 + \vec{p}_2) \cdot \vec{D}_1}.
* \f]
* if \f$s_2>s_1\f$ then \f$s_1 = 1.0\f$ otherwise \f$s_2 = 1.0\f$.
* These are then used to determine the value of the clusters vertex as
* \f[ X = \frac{1}{2} ( x_1 +x_2 + s_1 D_1 + s_2 D_2). \f]
*/
void calculateX();
/**
* Determines whether constituent p is perturbative or not.
*/
inline bool initPerturbative(tPPtr p);
/**
* This is needed to determine if a cluster is from a perturbative quark.
*/
static tcCluHadHdlPtr _clusterHadHandler;
/**
* The gluon mass is needed to determine if a cluster is from a perturbative quark
*/
static Energy2 _mg2;
/**
* Describe an abstract base class with persistent data.
*/
static ClassDescription<Cluster> initCluster;
bool _isAvailable; //!< Whether the cluster is hadronizing
tClusterPtr _reshufflingPartner; //!< The partner used in reshuffling
ParticleVector _component; //!< The constituent partons
tParticleVector _original; //!< The original components
vector<bool> _isBeamRemnant; //!< Whether a parton is a beam remnant
vector<bool> _isPerturbative; //!< Whether a parton is perturbative
int _numComp; //!< The number of constituents
long _id; //!< The id of this cluster
};
} // end namespace Herwig
#include "ThePEG/Utilities/ClassTraits.h"
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
/**
* The following template specialization informs ThePEG about the
* base class of Cluster.
*/
template <>
struct BaseClassTrait<Herwig::Cluster,1> {
/** Typedef of the base class of Cluster. */
typedef Particle NthBase;
};
/**
* The following template specialization informs ThePEG about the
* name of this class and the shared object where it is defined.
*/
template <>
struct ClassTraits<Herwig::Cluster>:
public ClassTraitsBase<Herwig::Cluster> {
/** Return the class name. */
static string className() { return "Herwig::Cluster"; }
};
/** @endcond */
}
#include "Cluster.icc"
#endif // HERWIG_Cluster_H
diff --git a/Hadronization/ColourReconnector.cc b/Hadronization/ColourReconnector.cc
--- a/Hadronization/ColourReconnector.cc
+++ b/Hadronization/ColourReconnector.cc
@@ -1,64 +1,212 @@
// -*- C++ -*-
//
// ColourReconnector.cc 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.
//
//
// This is the implementation of the non-inlined, non-templated member
// functions of the ColourReconnector class.
//
#include "ColourReconnector.h"
+#include "Cluster.h"
+
#include <ThePEG/Interface/ClassDocumentation.h>
#include <ThePEG/Interface/Switch.h>
+#include "ThePEG/Interface/Parameter.h"
#include <ThePEG/Persistency/PersistentOStream.h>
#include <ThePEG/Persistency/PersistentIStream.h>
-#include <ThePEG/Repository/EventGenerator.h>
+#include <ThePEG/Repository/UseRandom.h>
+
+#include <algorithm>
using namespace Herwig;
+
+void ColourReconnector::rearrange(EventHandler & ch,
+ ClusterVector & clusters) {
+ if (_clreco == 0) return;
+
+ ClusterVector newClusters = clusters;
+
+ // try avoiding systematic errors by randomizing the reconnection order
+ long (*p_irnd)(long) = UseRandom::irnd;
+ random_shuffle( newClusters.begin(), newClusters.end(), p_irnd );
+
+ // iterate over all clusters
+ for (ClusterVector::iterator currentCl=newClusters.begin();
+ currentCl != newClusters.end(); currentCl++) {
+
+ // find cluster, where the new clusters are lighter
+ ClusterPtr candidate = _findRecoPartner(*currentCl, newClusters);
+
+ // skip this cluster if no possible reshuffling partner can be found
+ if (candidate == *currentCl) {
+ continue;
+ }
+
+ // accept the reconnection with probability _preco.
+ if (UseRandom::rnd() < _preco) {
+
+ pair <ClusterPtr,ClusterPtr> reconnected =
+ _reconnect(*currentCl, candidate);
+
+ // reset children-parents relations:
+ _get3(*currentCl)->abandonChild(*currentCl);
+ _get3(*currentCl)->addChild(reconnected.first);
+ _getAnti3(*currentCl)->abandonChild(*currentCl);
+ _getAnti3(*currentCl)->addChild(reconnected.second);
+ _get3(candidate)->abandonChild(candidate);
+ _get3(candidate)->addChild(reconnected.second);
+ _getAnti3(candidate)->abandonChild(candidate);
+ _getAnti3(candidate)->addChild(reconnected.first);
+
+ // Replace the clusters in the ClusterVector. The order of the partons in
+ // the cluster vector carrying colour (i.e. not anticolour) is preserved.
+
+ // replace *currentCl by reconnected.first
+ replace( newClusters.begin(), newClusters.end(), *currentCl,
+ reconnected.first );
+
+ // replace candidate by reconnected.second
+ replace( newClusters.begin(), newClusters.end(), candidate,
+ reconnected.second );
+ }
+ }
+
+ // override pristine clusters with the new ones
+ swap(clusters,newClusters);
+}
+
+
+ClusterPtr ColourReconnector::_findRecoPartner(ClusterPtr cl,
+ ClusterVector cv) const {
+
+ ClusterPtr candidate = cl;
+ Energy minMass = 1*TeV;
+ for (ClusterVector::const_iterator cit=cv.begin(); cit != cv.end(); ++cit) {
+
+ // don't allow colour octet clusters
+ if ( _isColour8( _get3(cl),
+ _getAnti3(*cit) ) ||
+ _isColour8( _get3(*cit),
+ _getAnti3(cl) ) ) {
+ continue;
+ }
+
+ // momenta of the old clusters
+ Lorentz5Momentum p1 = _get3(cl)->momentum() +
+ _getAnti3(cl)->momentum();
+ Lorentz5Momentum p2 = _get3(*cit)->momentum() +
+ _getAnti3(*cit)->momentum();
+
+ // momenta of the new clusters
+ Lorentz5Momentum p3 = _get3(cl)->momentum() +
+ _getAnti3(*cit)->momentum();
+ Lorentz5Momentum p4 = _get3(*cit)->momentum() +
+ _getAnti3(cl)->momentum();
+
+ Energy oldMass = abs( p1.m() ) + abs( p2.m() );
+ Energy newMass = abs( p3.m() ) + abs( p4.m() );
+
+ if ( newMass < oldMass && newMass < minMass ) {
+ minMass = newMass;
+ candidate = *cit;
+ }
+ }
+ return candidate;
+}
+
+
+tPPtr ColourReconnector::_getAnti3(ClusterPtr cl) const {
+ if ( cl->_original[0]->hasAntiColour() ) {
+ return cl->_original[0];
+ } else if ( cl->_original[1]->hasAntiColour() ) {
+ return cl->_original[1];
+ } else {
+ return tPPtr();
+ }
+}
+
+
+tPPtr ColourReconnector::_get3(ClusterPtr cl) const {
+ if ( cl->_original[0]->hasColour() ) {
+ return cl->_original[0];
+ } else if ( cl->_original[1]->hasColour() ) {
+ return cl->_original[1];
+ } else {
+ return tPPtr();
+ }
+}
+
+
+bool ColourReconnector::_isColour8(tPPtr p1, tPPtr p2) const {
+ bool octet = false;
+ // make sure we have a triplet and an anti-triplet
+ if ( ( p1->hasColour() && p2->hasAntiColour() ) ||
+ ( p1->hasAntiColour() && p2->hasColour() ) ) {
+ if ( p1->parents().size()>0 && p2->parents().size()>0 ) {
+ // true if p1 and p2 are originated from the same gluon
+ octet = ( p1->parents()[0] == p2->parents()[0] ) &&
+ ( p1->parents()[0]->data().iColour() == PDT::Colour8 );
+ }
+ }
+ return octet;
+}
+
+
+pair <ClusterPtr,ClusterPtr> ColourReconnector::_reconnect(ClusterPtr c1,
+ ClusterPtr c2) const {
+ // choose the other possibility to form two clusters, that have no netto
+ // colour
+ ClusterPtr newCluster1 = new_ptr( Cluster( _get3(c1),
+ _getAnti3(c2) ) );
+ ClusterPtr newCluster2 = new_ptr( Cluster( _get3(c2),
+ _getAnti3(c1) ) );
+ return pair <ClusterPtr,ClusterPtr> (newCluster1,newCluster2);
+}
+
+
void ColourReconnector::persistentOutput(PersistentOStream & os) const {
- os << _clreco;
+ os << _clreco << _preco;
}
void ColourReconnector::persistentInput(PersistentIStream & is, int) {
- is >> _clreco;
+ is >> _clreco >> _preco;
}
ClassDescription<ColourReconnector> ColourReconnector::initColourReconnector;
// Definition of the static class description member.
void ColourReconnector::Init() {
static ClassDocumentation<ColourReconnector> documentation
("This class is responsible of the colour reconnection.");
static Switch<ColourReconnector,int> interfaceColourReconnection
("ColourReconnection",
"Colour reconnections",
&ColourReconnector::_clreco, 0, true, false);
static SwitchOption interfaceColourReconnectionOff
(interfaceColourReconnection,
"No",
"Colour reconnections off",
0);
static SwitchOption interfaceColourReconnectionOn
(interfaceColourReconnection,
"Yes",
"Colour reconnections on",
1);
+ static Parameter<ColourReconnector,double> interfaceRecoProb
+ ("ReconnectionProbability",
+ "Probability that a found reconnection possibility is actually accepted",
+ &ColourReconnector::_preco, 0.5, 0.0, 1.0,
+ false, false, Interface::limited);
+
}
-
-
-void ColourReconnector::rearrange(EventHandler &,
- ClusterVector &)
- {
- if (_clreco != 0)
- throw Exception("Colour reconnection not implemented.",Exception::abortnow);
-}
diff --git a/Hadronization/ColourReconnector.h b/Hadronization/ColourReconnector.h
--- a/Hadronization/ColourReconnector.h
+++ b/Hadronization/ColourReconnector.h
@@ -1,154 +1,191 @@
// -*- C++ -*-
//
// ColourReconnector.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_ColourReconnector_H
#define HERWIG_ColourReconnector_H
#include <ThePEG/Interface/Interfaced.h>
#include "CluHadConfig.h"
#include "ColourReconnector.fh"
namespace Herwig {
using namespace ThePEG;
/** \ingroup Hadronization
* \class ColourReconnector
* \brief Class for changing colour reconnections of partons.
* \author Alberto Ribon
*
* This class does the nonperturbative colour rearrangement, after the
* nonperturbative gluon splitting and the "normal" cluster formation.
* It uses the list of particles in the event record, and the collections of
* "usual" clusters which is passed to the main method. If the colour
* reconnection is actually accepted, then the previous collections of "usual"
* clusters is first deleted and then the new one is created.
*
- * Note: by default this class does nothing. It can be inherited and overridden
- * in future hadronization models.
* * @see \ref ColourReconnectorInterfaces "The interfaces"
* defined for ColourReconnector.
*/
class ColourReconnector: public Interfaced {
public:
/** @name Standard constructors and destructors. */
//@{
/**
* Default constructor.
*/
inline ColourReconnector();
//@}
/**
* Does the colour rearrangment.
*
* Does the colour rearrangement, starting from the list of particles
* in the event record, and the collection of "usual" clusters passed
* in input. If the actual rearrangement is accepted, the new collection
* of clusters is overriden to the intial one.
*/
void rearrange(EventHandler & ch,
ClusterVector & clusters);
public:
/** @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);
//@}
/**
* Standard Init function used to initialize the interfaces.
*/
static void Init();
protected:
/** @name Clone Methods. */
//@{
/**
* Make a simple clone of this object.
* @return a pointer to the new object.
*/
virtual IBPtr clone() const;
/** 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;
//@}
private:
/**
* Describe a concrete class with persistent data.
*/
static ClassDescription<ColourReconnector> initColourReconnector;
/**
* Private and non-existent assignment operator.
*/
ColourReconnector & operator=(const ColourReconnector &);
/**
* Do we do colour reconnections?
*/
int _clreco;
+
+ /**
+ * Probability that a found reconnection possibility is actually accepted.
+ */
+ double _preco;
+
+
+private:
+
+ /** Returns the Cluster (within the ClusterVector cv) where the sum of the
+ * invariant Cluster masses becomes minimal in the case of a colour
+ * reconnection with cl. If no reconnection partner can be found, a pointer to
+ * the original Cluster cl is returned.
+ */
+ ClusterPtr _findRecoPartner(ClusterPtr cl, ClusterVector cv) const;
+
+ /**
+ * @return the anticoloured constituent of a cluster, i.e. an antiquark or
+ * a diquark
+ */
+ tPPtr _getAnti3(ClusterPtr cl) const;
+
+ /**
+ * @return the coloured constituent of a cluster, i.e. a quark or an
+ * antidiquark
+ */
+ tPPtr _get3(ClusterPtr cl) const;
+
+ /**
+ * @return true, if the the two partons are splitting products of the same
+ * gluon
+ */
+ bool _isColour8(tPPtr p1, tPPtr p2) const;
+
+ /** Reconnects the constituents of the given clusters to the (only)other
+ * possible cluster combination.
+ */
+ pair <ClusterPtr,ClusterPtr> _reconnect(ClusterPtr c1, ClusterPtr c2) const;
+
};
}
namespace ThePEG {
/** @cond TRAITSPECIALIZATIONS */
template <>
/**
* The following template specialization informs ThePEG about the
* base class of ColourReconnector.
*/
struct BaseClassTrait<Herwig::ColourReconnector,1> {
/** Typedef of the base class of ColourReconnector. */
typedef Interfaced NthBase;
};
template <>
/**
* The following template specialization informs ThePEG about the
* name of this class and the shared object where it is defined.
*/
struct ClassTraits<Herwig::ColourReconnector>
: public ClassTraitsBase<Herwig::ColourReconnector> {
/** Return the class name.*/
static string className() { return "Herwig::ColourReconnector"; }
};
/** @endcond */
}
#include "ColourReconnector.icc"
#endif /* HERWIG_ColourReconnector_H */
diff --git a/Hadronization/ColourReconnector.icc b/Hadronization/ColourReconnector.icc
--- a/Hadronization/ColourReconnector.icc
+++ b/Hadronization/ColourReconnector.icc
@@ -1,26 +1,28 @@
// -*- C++ -*-
//
// ColourReconnector.icc 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.
//
//
// This is the implementation of the inlined member functions of
// the ColourReconnector class.
//
namespace Herwig {
-inline ColourReconnector::ColourReconnector() : _clreco( 0 )
+inline ColourReconnector::ColourReconnector() :
+ _clreco( 0 ),
+ _preco( 0.5 )
{}
inline IBPtr ColourReconnector::clone() const {
return new_ptr(*this);
}
inline IBPtr ColourReconnector::fullclone() const {
return new_ptr(*this);
}
}

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