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diff --git a/Shower/Default/FS_QTildeShowerKinematics1to2.cc b/Shower/Default/FS_QTildeShowerKinematics1to2.cc
--- a/Shower/Default/FS_QTildeShowerKinematics1to2.cc
+++ b/Shower/Default/FS_QTildeShowerKinematics1to2.cc
@@ -1,218 +1,225 @@
// -*- C++ -*-
//
// FS_QTildeShowerKinematics1to2.cc is a part of Herwig++ - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2011 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 FS_QTildeShowerKinematics1to2 class.
//
#include "FS_QTildeShowerKinematics1to2.h"
#include "ThePEG/PDT/EnumParticles.h"
#include "Herwig++/Shower/SplittingFunctions/SplittingFunction.h"
#include "Herwig++/Shower/Base/ShowerParticle.h"
#include "ThePEG/Utilities/Debug.h"
#include "Herwig++/Shower/ShowerHandler.h"
#include "Herwig++/Shower/Base/Evolver.h"
#include "Herwig++/Shower/Base/PartnerFinder.h"
#include "Herwig++/Shower/Base/ShowerModel.h"
#include "Herwig++/Shower/Base/KinematicsReconstructor.h"
#include "Herwig++/Shower/Base/ShowerVertex.h"
using namespace Herwig;
void FS_QTildeShowerKinematics1to2::
updateParameters(tShowerParticlePtr theParent,
tShowerParticlePtr theChild0,
tShowerParticlePtr theChild1,
bool setAlpha) const {
const ShowerParticle::Parameters & parent = theParent->showerParameters();
ShowerParticle::Parameters & child0 = theChild0->showerParameters();
ShowerParticle::Parameters & child1 = theChild1->showerParameters();
// determine alphas of children according to interpretation of z
if ( setAlpha ) {
child0.alpha = z() * parent.alpha;
child1.alpha = (1.-z()) * parent.alpha;
}
// set the values
double cphi = cos(phi());
double sphi = sin(phi());
child0.ptx = pT() * cphi + z() * parent.ptx;
child0.pty = pT() * sphi + z() * parent.pty;
child0.pt = sqrt( sqr(child0.ptx) + sqr(child0.pty) );
child1.ptx = -pT() * cphi + (1.-z())* parent.ptx;
child1.pty = -pT() * sphi + (1.-z())* parent.pty;
child1.pt = sqrt( sqr(child1.ptx) + sqr(child1.pty) );
}
void FS_QTildeShowerKinematics1to2::
updateChildren(const tShowerParticlePtr parent,
const ShowerParticleVector & children,
ShowerPartnerType::Type partnerType) const {
assert(children.size()==2);
// calculate the scales
splittingFn()->evaluateFinalStateScales(partnerType,scale(),z(),parent,
children[0],children[1]);
// update the parameters
updateParameters(parent, children[0], children[1], true);
// set up the colour connections
splittingFn()->colourConnection(parent,children[0],children[1],partnerType,false);
// make the products children of the parent
parent->addChild(children[0]);
parent->addChild(children[1]);
// set the momenta of the children
for(ShowerParticleVector::const_iterator pit=children.begin();
pit!=children.end();++pit) {
setMomentum(*pit,true);
}
// sort out the helicity stuff
if(! ShowerHandler::currentHandler()->evolver()->correlations()) return;
SpinPtr pspin(parent->spinInfo());
if(!pspin || !ShowerHandler::currentHandler()->evolver()->spinCorrelations() ) return;
Energy2 t = sqr(scale())*z()*(1.-z());
IdList ids;
ids.push_back(parent->id());
ids.push_back(children[0]->id());
ids.push_back(children[1]->id());
// create the vertex
SVertexPtr vertex(new_ptr(ShowerVertex()));
// set the matrix element
vertex->ME(splittingFn()->matrixElement(z(),t,ids,phi()));
// set the incoming particle for the vertex
parent->spinInfo()->decayVertex(vertex);
for(ShowerParticleVector::const_iterator pit=children.begin();
pit!=children.end();++pit) {
// construct the spin info for the children
constructSpinInfo(*pit,true);
// connect the spinInfo object to the vertex
(*pit)->spinInfo()->productionVertex(vertex);
}
}
void FS_QTildeShowerKinematics1to2::
reconstructParent(const tShowerParticlePtr parent,
const ParticleVector & children ) const {
assert(children.size() == 2);
ShowerParticlePtr c1 = dynamic_ptr_cast<ShowerParticlePtr>(children[0]);
ShowerParticlePtr c2 = dynamic_ptr_cast<ShowerParticlePtr>(children[1]);
parent->showerParameters().beta=
c1->showerParameters().beta + c2->showerParameters().beta;
parent->set5Momentum( c1->momentum() + c2->momentum() );
}
void FS_QTildeShowerKinematics1to2::reconstructLast(const tShowerParticlePtr last,
Energy mass) const {
// set beta component and consequently all missing data from that,
// using the nominal (i.e. PDT) mass.
Energy theMass = mass > ZERO ? mass : last->data().constituentMass();
ShowerParticle::Parameters & lastParam = last->showerParameters();
lastParam.beta = ( sqr(theMass) + sqr(lastParam.pt) - sqr(lastParam.alpha) * pVector().m2() )
/ ( 2. * lastParam.alpha * p_dot_n() );
// set that new momentum
- last->set5Momentum(sudakov2Momentum( lastParam.alpha, lastParam.beta,
- lastParam.ptx , lastParam.pty) );
+ Lorentz5Momentum newMomentum = sudakov2Momentum( lastParam.alpha, lastParam.beta,
+ lastParam.ptx , lastParam.pty);
+ if(last->data().stable()) {
+ last->set5Momentum( newMomentum );
+ }
+ else {
+ last->boost(last->momentum().findBoostToCM());
+ last->boost(newMomentum.boostVector());
+ }
}
void FS_QTildeShowerKinematics1to2::initialize(ShowerParticle & particle,PPtr) {
// set the basis vectors
Lorentz5Momentum p,n;
Frame frame;
if(particle.perturbative()!=0) {
// find the partner and its momentum
ShowerParticlePtr partner=particle.partner();
Lorentz5Momentum ppartner(partner->momentum());
// momentum of the emitting particle
p = particle.momentum();
Lorentz5Momentum pcm;
// if the partner is a final-state particle then the reference
// vector is along the partner in the rest frame of the pair
if(partner->isFinalState()) {
Boost boost=(p + ppartner).findBoostToCM();
pcm = ppartner;
pcm.boost(boost);
n = Lorentz5Momentum(ZERO,pcm.vect());
n.boost( -boost);
}
else if(!partner->isFinalState()) {
// if the partner is an initial-state particle then the reference
// vector is along the partner which should be massless
if(particle.perturbative()==1)
{n = Lorentz5Momentum(ZERO,ppartner.vect());}
// if the partner is an initial-state decaying particle then the reference
// vector is along the backwards direction in rest frame of decaying particle
else {
Boost boost=ppartner.findBoostToCM();
pcm = p;
pcm.boost(boost);
n = Lorentz5Momentum( ZERO, -pcm.vect());
n.boost( -boost);
}
}
frame = BackToBack;
}
else if(particle.initiatesTLS()) {
tShoKinPtr kin=dynamic_ptr_cast<ShowerParticlePtr>
(particle.parents()[0]->children()[0])->showerKinematics();
p = kin->getBasis()[0];
n = kin->getBasis()[1];
frame = kin->frame();
}
else {
tShoKinPtr kin=dynamic_ptr_cast<ShowerParticlePtr>(particle.parents()[0])
->showerKinematics();
p = kin->getBasis()[0];
n = kin->getBasis()[1];
frame = kin->frame();
}
// set the basis vectors
setBasis(p,n,frame);
}
void FS_QTildeShowerKinematics1to2::updateParent(const tShowerParticlePtr parent,
const ShowerParticleVector & children,
ShowerPartnerType::Type) const {
IdList ids(3);
ids[0] = parent->id();
ids[1] = children[0]->id();
ids[2] = children[1]->id();
const vector<Energy> & virtualMasses = SudakovFormFactor()->virtualMasses(ids);
if(children[0]->children().empty()) children[0]->virtualMass(virtualMasses[1]);
if(children[1]->children().empty()) children[1]->virtualMass(virtualMasses[2]);
// compute the new pT of the branching
Energy2 pt2=sqr(z()*(1.-z()))*sqr(scale())
- sqr(children[0]->virtualMass())*(1.-z())
- sqr(children[1]->virtualMass())* z() ;
if(ids[0]!=ParticleID::g) pt2 += z()*(1.-z())*sqr(virtualMasses[0]);
Energy2 q2 =
sqr(children[0]->virtualMass())/z() +
sqr(children[1]->virtualMass())/(1.-z()) +
pt2/z()/(1.-z());
if(pt2<ZERO) {
parent->virtualMass(ZERO);
}
else {
parent->virtualMass(sqrt(q2));
pT(sqrt(pt2));
}
}
void FS_QTildeShowerKinematics1to2::
resetChildren(const tShowerParticlePtr parent,
const ShowerParticleVector & children) const {
updateParameters(parent, children[0], children[1], false);
for(unsigned int ix=0;ix<children.size();++ix) {
if(children[ix]->children().empty()) continue;
ShowerParticleVector newChildren;
for(unsigned int iy=0;iy<children[ix]->children().size();++iy)
newChildren.push_back(dynamic_ptr_cast<ShowerParticlePtr>
(children[ix]->children()[iy]));
children[ix]->showerKinematics()->resetChildren(children[ix],newChildren);
}
}

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