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// -*- C++ -*-
//
// MEee2gZ2qq.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 MEee2gZ2qq class.
//
#include "MEee2gZ2qq.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;
MEee2gZ2qq::MEee2gZ2qq()
: coefs(20), mZ2(ZERO), GZ2(ZERO), lastCont(0.0), lastBW(0.0) {}
unsigned int MEee2gZ2qq::orderInAlphaS() const {
return 0;
}
unsigned int MEee2gZ2qq::orderInAlphaEW() const {
return 2;
}
void MEee2gZ2qq::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 = 1; i <= maxFlavour(); ++i ) {
tcPDPtr q = getParticleData(i);
tcPDPtr qb = q->CC();
add(new_ptr((Tree2toNDiagram(2), em, ep, 1, gamma, 3, q, 3, qb, -1)));
add(new_ptr((Tree2toNDiagram(2), em, ep, 1, Z0, 3, q, 3, qb, -2)));
}
}
Energy2 MEee2gZ2qq::scale() const {
return sHat();
}
double MEee2gZ2qq::me2() const {
Energy2 m2 = meMomenta()[2].mass2();
// Energy2 p1p3 = 0.5*(m2 - tHat());
// Energy2 p1p2 = 0.5*sHat();
Energy2 p1p3 = meMomenta()[0].dot(meMomenta()[2]);
Energy2 p1p2 = meMomenta()[0].dot(meMomenta()[1]);
Energy4 pt2 = sqr(p1p3);
Energy4 pts = p1p3*p1p2;
Energy4 ps2 = sqr(p1p2);
Energy4 psm = p1p2*m2;
int up = abs(mePartonData()[2]->id() + 1)%2;
lastCont =
(coefs[0 + up]*(pt2 - pts) + coefs[2 + up]*(ps2 + psm))/sqr(sHat());
double intr = 0.25*(coefs[4 + up]*pt2 + coefs[6 + up]*pts +
coefs[8 + up]*ps2 + coefs[10 + up]*psm)*
(sHat() - mZ2)/(sHat()*(sqr(sHat() - mZ2) + mZ2*GZ2));
lastBW = 0.25*(coefs[12 + up]*pt2 + coefs[14 + up]*pts +
coefs[16 + up]*ps2 + coefs[18 + up]*psm)/
(sqr(sHat() - mZ2) + mZ2*GZ2);
double alphaS = SM().alphaS(scale());
int Nf = SM().Nf(scale());
DVector save;
meInfo(save << lastCont << lastBW);
return (lastCont + intr + lastBW)*sqr(SM().alphaEM(scale()))*
(1.0 + alphaS/Constants::pi + (1.986-0.115*Nf)*sqr(alphaS/Constants::pi));
}
Selector<MEee2gZ2qq::DiagramIndex>
MEee2gZ2qq::diagrams(const DiagramVector & diags) const {
if ( lastXCombPtr() ) {
lastCont = meInfo()[0];
lastBW = meInfo()[1];
}
Selector<DiagramIndex> sel;
for ( DiagramIndex i = 0; i < diags.size(); ++i ) {
if ( diags[i]->id() == -1 ) sel.insert(lastCont, i);
else if ( diags[i]->id() == -2 ) sel.insert(lastBW, i);
}
return sel;
}
Selector<const ColourLines *>
MEee2gZ2qq::colourGeometries(tcDiagPtr) const {
static ColourLines c("-5 4");
Selector<const ColourLines *> sel;
sel.insert(1.0, &c);
return sel;
}
IBPtr MEee2gZ2qq::clone() const {
return new_ptr(*this);
}
IBPtr MEee2gZ2qq::fullclone() const {
return new_ptr(*this);
}
void MEee2gZ2qq::doinit() {
double C = sqr(4.0*Constants::pi)/3.0;
double SW2 = SM().sin2ThetaW();
double SW4 = sqr(SW2);
double SW6 = SW2*SW4;
double SW8 = SW2*SW6;
double CW2 = 1.0 - SW2;
coefs[0] = 16.0*C;
coefs[1] = 64.0*C;
coefs[2] = 8.0*C;
coefs[3] = 32.0*C;
C /= (CW2*SW2);
coefs[4] = 4.0*(32.0*SW4 - 32.0*SW2 + 6.0)*C;
coefs[5] = 8.0*(64.0*SW4 - 40.0*SW2 + 6.0)*C;
coefs[6] = -4.0*(32.0*SW4 - 32.0*SW2 + 12.0)*C;
coefs[7] = -8.0*(64.0*SW4 - 40.0*SW2 + 12.0)*C;
coefs[8] = 4.0*(16.0*SW4 - 16.0*SW2 + 6.0)*C;
coefs[9] = 8.0*(32.0*SW4 - 20.0*SW2 + 6.0)*C;
coefs[10] = 4.0*(16.0*SW4 - 16.0*SW2 + 3.0)*C;
coefs[11] = 8.0*(32.0*SW4 - 20.0*SW2 + 3.0)*C;
C /= (CW2*SW2);
coefs[12] = ( 64.0*SW8 - 128.0*SW6 + 128.0*SW4 - 48.0*SW2 + 9.0)*C;
coefs[13] = (256.0*SW8 - 320.0*SW6 + 200.0*SW4 - 60.0*SW2 + 9.0)*C;
coefs[14] = -( 64.0*SW8 - 128.0*SW6 + 176.0*SW4 - 96.0*SW2 + 18.0)*C;
coefs[15] = -(256.0*SW8 - 320.0*SW6 + 296.0*SW4 - 120.0*SW2 + 18.0)*C;
coefs[16] = ( 32.0*SW8 - 64.0*SW6 + 88.0*SW4 - 48.0*SW2 + 9.0)*C;
coefs[17] = (128.0*SW8 - 160.0*SW6 + 148.0*SW4 - 60.0*SW2 + 9.0)*C;
coefs[18] = ( 32.0*SW8 - 64.0*SW6 + 28.0*SW4 - 6.0*SW2)*C;
coefs[19] = (128.0*SW8 - 160.0*SW6 + 64.0*SW4 - 12.0*SW2)*C;
tcPDPtr Z0 = getParticleData(ParticleID::Z0);
mZ2 = sqr(Z0->mass());
GZ2 = sqr(Z0->width());
ME2to2QCD::doinit();
}
void MEee2gZ2qq::persistentOutput(PersistentOStream & os) const {
os << coefs << ounit(mZ2, GeV2) << ounit(GZ2, GeV2) << lastCont << lastBW;
}
void MEee2gZ2qq::persistentInput(PersistentIStream & is, int) {
is >> coefs >> iunit(mZ2, GeV2) >> iunit(GZ2, GeV2) >> lastCont >> lastBW;
}
ClassDescription<MEee2gZ2qq> MEee2gZ2qq::initMEee2gZ2qq;
void MEee2gZ2qq::Init() {
static ClassDocumentation<MEee2gZ2qq> documentation
("The ThePEG::MEee2gZ2qq class implements the full"
"\\f$e^+e^- \\rightarrow \\gamma/Z^0 \\rightarrow q\\bar{q}\\f$ "
"matrix element including the interference terms.");
}
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