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IILightInvertedTildeKinematics.cc
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IILightInvertedTildeKinematics.cc
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// -*- C++ -*-
//
// IILightInvertedTildeKinematics.cc is a part of Herwig++ - A multi-purpose Monte Carlo event generator
// Copyright (C) 2002-2012 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 IILightInvertedTildeKinematics class.
//
#include "IILightInvertedTildeKinematics.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Repository/EventGenerator.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
using namespace Herwig;
IILightInvertedTildeKinematics::IILightInvertedTildeKinematics() {}
IILightInvertedTildeKinematics::~IILightInvertedTildeKinematics() {}
IBPtr IILightInvertedTildeKinematics::clone() const {
return new_ptr(*this);
}
IBPtr IILightInvertedTildeKinematics::fullclone() const {
return new_ptr(*this);
}
bool IILightInvertedTildeKinematics::doMap(const double * r) {
if ( ptMax() < ptCut() ) {
jacobian(0.0);
return false;
}
Lorentz5Momentum emitter = bornEmitterMomentum();
Lorentz5Momentum spectator = bornSpectatorMomentum();
double mapping = 1.0;
pair<Energy,double> ptz = generatePtZ(mapping,r);
if ( mapping == 0.0 ) {
jacobian(0.0);
return false;
}
Energy pt = ptz.first;
double z = ptz.second;
double ratio = sqr(pt/lastScale());
double x = z*(1.-z) / ( 1. - z + ratio );
double v = ratio * z / ( 1. - z + ratio );
if ( x < emitterX() || x > 1. ||
v > 1. || v > 1.-x ) {
jacobian(0.0);
return false;
}
mapping /= z*(1.-z);
jacobian(mapping*(sqr(lastScale())/sHat())/(16.*sqr(Constants::pi)));
subtractionParameters().resize(2);
subtractionParameters()[0] = x;
subtractionParameters()[1] = v;
double phi = 2.*Constants::pi*r[2];
Lorentz5Momentum kt = getKt(emitter,spectator,pt,phi);
realEmitterMomentum() = (1./x)*emitter;
realEmissionMomentum() = ((1.-x-v)/x)*emitter+v*spectator+kt;
realSpectatorMomentum() = spectator;
K = realEmitterMomentum() + realSpectatorMomentum() - realEmissionMomentum();
K2 = K.m2();
Ktilde = emitter + spectator;
KplusKtilde = K + Ktilde;
KplusKtilde2 = KplusKtilde.m2();
realEmitterMomentum().setMass(ZERO);
realEmitterMomentum().rescaleEnergy();
realEmissionMomentum().setMass(ZERO);
realEmissionMomentum().rescaleEnergy();
realSpectatorMomentum().setMass(ZERO);
realSpectatorMomentum().rescaleEnergy();
return true;
}
Energy IILightInvertedTildeKinematics::lastPt() const {
Energy scale = sqrt(2.*(bornEmitterMomentum()*bornSpectatorMomentum()));
double x = subtractionParameters()[0];
double v = subtractionParameters()[1];
return scale * sqrt(v*(1.-x-v)/x);
}
Energy IILightInvertedTildeKinematics::ptMax() const {
double tau = emitterX()*spectatorX();
return (1.-tau)*lastScale()/(2.*sqrt(tau));
}
pair<double,double> IILightInvertedTildeKinematics::zBounds(Energy pt) const {
double tau = emitterX()*spectatorX();
double s = sqrt(1.-sqr(pt/ptMax()));
return make_pair(0.5*(1.+tau-(1.-tau)*s),0.5*(1.+tau+(1.-tau)*s));
}
// If needed, insert default implementations of virtual function defined
// in the InterfacedBase class here (using ThePEG-interfaced-impl in Emacs).
void IILightInvertedTildeKinematics::persistentOutput(PersistentOStream &) const {
}
void IILightInvertedTildeKinematics::persistentInput(PersistentIStream &, int) {
}
void IILightInvertedTildeKinematics::Init() {
static ClassDocumentation<IILightInvertedTildeKinematics> documentation
("IILightInvertedTildeKinematics inverts the initial-initial tilde "
"kinematics.");
}
// *** Attention *** The following static variable is needed for the type
// description system in ThePEG. Please check that the template arguments
// are correct (the class and its base class), and that the constructor
// arguments are correct (the class name and the name of the dynamically
// loadable library where the class implementation can be found).
DescribeClass<IILightInvertedTildeKinematics,InvertedTildeKinematics>
describeHerwigIILightInvertedTildeKinematics("Herwig::IILightInvertedTildeKinematics", "HwMatchbox.so");

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