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ShowerHandler.cc
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ShowerHandler.cc
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// -*- C++ -*-
//
// This is the implementation of the non-inlined, non-templated member
// functions of the ShowerHandler class.
//
#include "ShowerHandler.h"
#include "ThePEG/PDT/DecayMode.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Interface/Reference.h"
#include "ThePEG/Interface/Parameter.h"
#include "ThePEG/Handlers/XComb.h"
#include "ThePEG/Utilities/Timer.h"
#include "Evolver.h"
#include "Herwig++/Shower/Kinematics/ShowerParticle.h"
#include "Herwig++/Utilities/EnumParticles.h"
#include "Herwig++/Hadronization/Remnant.h"
#include <cassert>
#ifdef ThePEG_TEMPLATES_IN_CC_FILE
// #include "ShowerHandler.tcc"
#endif
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
#include "ThePEG/Repository/EventGenerator.h"
#include "ShowerTree.h"
using namespace Herwig;
void ShowerHandler::persistentOutput(PersistentOStream & os) const {
os << _evolver << _maxtry;
}
void ShowerHandler::persistentInput(PersistentIStream & is, int) {
is >> _evolver >> _maxtry;
}
ClassDescription<ShowerHandler> ShowerHandler::initShowerHandler;
// Definition of the static class description member.
void ShowerHandler::Init() {
static ClassDocumentation<ShowerHandler> documentation
("Main driver class for the showering.");
static Reference<ShowerHandler,Evolver>
interfaceEvolver("Evolver",
"A reference to the Evolver object",
&Herwig::ShowerHandler::_evolver,
false, false, true, false);
static Parameter<ShowerHandler,unsigned int> interfaceMaxTry
("MaxTry",
"The maximum number of attempts for the main showering loop",
&ShowerHandler::_maxtry, 10, 1, 100,
false, false, Interface::limited);
}
void ShowerHandler::fillEventRecord()
{
// create a new step
StepPtr pstep = eventHandler()->newStep();
if(_done.empty()) throw Exception() << "Must have some showers to insert in "
<< "ShowerHandler::fillEventRecord()"
<< Exception::runerror;
if(!_done[0]->isHard()) throw Exception() << "Must start filling with hard process"
<< " in ShowerHandler::fillEventRecord()"
<< Exception::runerror;
// insert the steps
for(unsigned int ix=0;ix<_done.size();++ix)
{
_done[ix]->fillEventRecord(pstep,
_evolver->isISRadiationON(),
_evolver->isFSRadiationON());
}
}
void ShowerHandler::findShoweringParticles()
{
Timer<1001> timer("ShowerHandler::findShoweringParticles");
// clear the storage
_hard=ShowerTreePtr();
_decay.clear();
_done.clear();
// temporary storage of the particles
set<PPtr> hardParticles;
// outgoing particles from the hard process
ParticleVector outgoing=eventHandler()->currentCollision()->
primarySubProcess()->outgoing();
set<PPtr> outgoingset(outgoing.begin(),outgoing.end());
// loop over the tagged particles
tParticleVector::const_iterator taggedP = tagged().begin();
for (;taggedP != tagged().end(); ++taggedP) {
// if a remnant don't consider
if(eventHandler()->currentCollision()->isRemnant(*taggedP))
continue;
// find the parent and if colourless s-channel resonance
bool isDecayProd=false;
tPPtr parent;
if(!(*taggedP)->parents().empty())
{
parent = (*taggedP)->parents()[0];
// check if from s channel decaying colourless particle
// (must be same as in findParent)
isDecayProd = !parent->dataPtr()->coloured() && parent->momentum().m2()>0.;
}
// add to list of outgoing hard particles if needed
if(outgoingset.find(*taggedP) != outgoingset.end())
{
if(isDecayProd) hardParticles.insert(findParent(parent));
else hardParticles.insert(*taggedP);
}
else
{throw Exception() << "Starting on decay not yet implemented in "
<< "ShowerHandler::findShoweringParticles()"
<< Exception::runerror;}
}
// there must be something to shower
if(hardParticles.empty())
throw Exception() << "No particles to shower in "
<< "ShowerHandler::fillShoweringParticles"
<< Exception::eventerror;
// create the hard process ShowerTree
ParticleVector out(hardParticles.begin(),hardParticles.end());
_hard=new_ptr(ShowerTree(eventHandler(),out,_evolver->showerVariables(),
_decay));
_hard->setParents();
}
void ShowerHandler::cascade()
{
Timer<1002> timer("ShowerHandler::cascade");
// start of the try block for the whole showering process
unsigned int countFailures=0;
ShowerTreePtr hard;
vector<ShowerTreePtr> decay;
while (countFailures<_maxtry) {
try
{
// set the gluon mass to be used in the reconstruction
_evolver->showerVariables()->setGluonMass(false);
// find the particles in the hard process and the decayed particles to shower
findShoweringParticles();
// check if a hard process or decay
bool isHard = _hard;
// find the stopping scale for the shower if multi-scale shower is on
Energy largestWidth = Energy();
if(_evolver->showerVariables()->isMultiScaleShowerON()&&!_decay.empty())
{
largestWidth=(*_decay.rbegin()).first;
if(largestWidth<
_evolver->showerVariables()->globalParameters()->hadronizationScale())
largestWidth = Energy();
}
// if a hard process perform the shower for the hard process
if(isHard)
{
_evolver->showerHardProcess(_hard);
_done.push_back(_hard);
_hard->updateAfterShower(_decay,eventHandler());
}
// if no decaying particles to shower break out of the loop
if(_decay.empty()) break;
// if no hard process
if(!isHard)
throw Exception() << "Shower starting with a decay is not yet implemented"
<< Exception::runerror;
// shower the decay products
while(!_decay.empty())
{
multimap<Energy,ShowerTreePtr>::iterator dit=--_decay.end();
while(!dit->second->parent()->hasShowered() && dit!=_decay.begin())
--dit;
// get the particle and the width
ShowerTreePtr decayingTree = dit->second;
// Energy largestWidthDecayingSystem=(*_decay.rbegin()).first;
// remove it from the multimap
_decay.erase(dit);
// make sure the particle has been decayed
decayingTree->decay(_decay,eventHandler());
// now shower the decay
_evolver->showerDecay(decayingTree);
_done.push_back(decayingTree);
decayingTree->updateAfterShower(_decay,eventHandler());
}
// suceeded break out of the loop
break;
}
catch (Veto)
{
throw Exception() << "Problem with throwing Veto in ShowerHandler at the moment"
<< Exception::eventerror;
++countFailures;
}
}
// if loop exited because of too many tries, throw event away
if (countFailures >= _maxtry) {
throw Exception() << "Too many tries for main while loop "
<< "in ShowerHandler::cascade()."
<< Exception::eventerror;
}
//enter the particles in the event record
fillEventRecord();
// remake the remnants (needs to be after the colours are sorted
// out in the insertion into the event record)
makeRemnants();
}
void ShowerHandler::makeRemnants()
{
// get the incoming particles
PPair incoming=generator()->currentEvent()->incoming();
ParticleVector in;
in.push_back(incoming.first);
in.push_back(incoming.second);
// get the remnants
tParticleSet remn=generator()->currentEvent()->primaryCollision()->getRemnants();
// fix the momenta
for(unsigned int ix=0;ix<in.size();++ix)
{
Lorentz5Momentum pnew;
ParticleVector prem,pother;
if(in[ix]->children().size()==1) continue;
for(unsigned int iy=0;iy<in[ix]->children().size();++iy)
{
if(remn.find(in[ix]->children()[iy])==remn.end())
{
pnew+=in[ix]->children()[iy]->momentum();
pother.push_back(in[ix]->children()[iy]);
}
else
prem.push_back(in[ix]->children()[iy]);
}
pnew=in[ix]->momentum()-pnew;
pnew.rescaleMass();
// throw exception if gone wrong
if(prem.size()!=1||pother.size()!=1)
throw Exception()
<< "Must be one and only 1 remnant for beam in ShowerHandler::makeRemnants()"
<< Exception::eventerror;
// remake the remnant
if(prem[0]->id()==ExtraParticleID::Remnant)
{
tRemnantPtr rem=dynamic_ptr_cast<tRemnantPtr>(prem[0]);
if(rem) rem->regenerate(pother[0],pnew);
}
}
}

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