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// -*- C++ -*-
//
// MENCDIS.cc is a part of ThePEG - Toolkit for HEP Event Generation
// Copyright (C) 1999-2011 Leif Lonnblad
//
// ThePEG 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 MENCDIS class.
//
#include "MENCDIS.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/PDT/EnumParticles.h"
#include "ThePEG/Repository/EventGenerator.h"
#include "ThePEG/StandardModel/StandardModelBase.h"
#include "ThePEG/Handlers/StandardXComb.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
using namespace ThePEG;
MENCDIS::MENCDIS()
: mZ2(ZERO) {}
MENCDIS::MENCDIS(const MENCDIS & x)
: ME2to2QCD(x), mZ2(x.mZ2) {}
MENCDIS::~MENCDIS() {}
unsigned int MENCDIS::orderInAlphaS() const {
return 0;
}
unsigned int MENCDIS::orderInAlphaEW() const {
return 2;
}
void MENCDIS::getDiagrams() const {
tcPDPtr gamma = getParticleData(ParticleID::gamma);
tcPDPtr Z0 = getParticleData(ParticleID::Z0);
tcPDPtr ep = getParticleData(ParticleID::eplus);
tcPDPtr em = getParticleData(ParticleID::eminus);
for ( int i = -maxFlavour(); i <= maxFlavour(); ++i ) {
if ( !i ) continue;
tcPDPtr q = getParticleData(i);
add(new_ptr((Tree2toNDiagram(3), q, gamma, em, 1, q, 2, em, -1)));
add(new_ptr((Tree2toNDiagram(3), q, Z0, em, 1, q, 2, em, -2)));
add(new_ptr((Tree2toNDiagram(3), q, gamma, ep, 1, q, 2, ep, -1)));
add(new_ptr((Tree2toNDiagram(3), q, Z0, ep, 1, q, 2, ep, -2)));
}
}
Energy2 MENCDIS::scale() const {
return -tHat();
}
double MENCDIS::me2() const {
double lastG = 0.0;
double lastIntr = 0.0;
double lastZ = 0.0;
//pq is a vector in the same direction as the quark with zero mass.
Lorentz5Momentum pq = meMomenta()[0];
pq.setMass(ZERO);
pq.rescaleEnergy();
double y = 1.0 - pq.dot(meMomenta()[3]) / pq.dot(meMomenta()[1]);
Energy4 F2Coeff = sqr(sHat()) * (1 + sqr(1-y));
Energy4 F3Coeff = sqr(sHat()) * (1 - sqr(1-y));
double C = 16 * SM().sin2ThetaW() * ( 1.0 - SM().sin2ThetaW() );
if(mePartonData()[0]->id() < 0){
F3Coeff = -F3Coeff;
}
if(mePartonData()[1]->id() < 0){
F3Coeff = -F3Coeff;
}
if( abs(mePartonData()[0]->id())%2 == 0 ){
lastG = F2Coeff * sqr(SM().eu()) / sqr(tHat());
lastIntr = -2*SM().eu()*(F2Coeff*SM().ve()*SM().vu() +
2*F3Coeff*SM().ae()*SM().au()) / (-tHat() * (-tHat() + mZ2) * C);
lastZ = ( F2Coeff * (sqr(SM().ae())+sqr(SM().ve())) *
(sqr(SM().au())+sqr(SM().vu())) + 4.0 * F3Coeff*SM().ve()*
SM().ae()*SM().au()*SM().vu() ) / sqr((-tHat() + mZ2) * C);
}
else{
lastG = F2Coeff * sqr(SM().ed()) / sqr(tHat());
lastIntr = -2*SM().ed()*(F2Coeff*SM().ve()*SM().vd() +
2*F3Coeff*SM().ae()*SM().ad()) / (-tHat() * (-tHat() + mZ2) * C);
lastZ = ( F2Coeff * (sqr(SM().ae())+sqr(SM().ve())) *
(sqr(SM().ad())+sqr(SM().vd())) + 4.0 * F3Coeff*SM().ve()*
SM().ae()*SM().ad()*SM().vd() ) / sqr((-tHat() + mZ2) * C);
}
DVector save;
meInfo(save << lastG << lastZ);
return (lastG + lastIntr + lastZ) * sqr(SM().alphaEM(scale())) *
32.0 * sqr(Constants::pi);
}
Selector<MENCDIS::DiagramIndex>
MENCDIS::diagrams(const DiagramVector & diags) const {
if ( lastXCombPtr() ) {
lastG = meInfo()[0];
lastZ = meInfo()[1];
}
Selector<DiagramIndex> sel;
for ( DiagramIndex i = 0; i < diags.size(); ++i ) {
if ( diags[i]->id() == -1 ) sel.insert(lastG, i);
else if ( diags[i]->id() == -2 ) sel.insert(lastZ, i);
}
return sel;
}
Selector<const ColourLines *>
MENCDIS::colourGeometries(tcDiagPtr diag) const {
static ColourLines c("1 4");
static ColourLines cb("-1 -4");
Selector<const ColourLines *> sel;
if ( diag->partons()[0]->id() > 0 )
sel.insert(1.0, &c);
else
sel.insert(1.0, &cb);
return sel;
}
IBPtr MENCDIS::clone() const {
return new_ptr(*this);
}
IBPtr MENCDIS::fullclone() const {
return new_ptr(*this);
}
void MENCDIS::doinit() {
ME2to2QCD::doinit();
tcPDPtr Z0 = getParticleData(ParticleID::Z0);
mZ2 = sqr(Z0->mass());
}
void MENCDIS::persistentOutput(PersistentOStream & os) const {
os << ounit(mZ2, GeV2) << lastG << lastZ;
}
void MENCDIS::persistentInput(PersistentIStream & is, int) {
is >> iunit(mZ2, GeV2) >> lastG >> lastZ;
}
ClassDescription<MENCDIS> MENCDIS::initMENCDIS;
void MENCDIS::Init() {
static ClassDocumentation<MENCDIS> documentation
("The ThePEG::MENCDIS class implements the full"
"\\f$e^\\pm q \\rightarrow e^\\pm q\\f$ "
"matrix element including the interference terms.");
}
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