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MEDiffraction.cc
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// -*- C++ -*-
//
// This is the implementation of the non-inlined, non-templated member
// functions of the MEDiffraction class.
//
#include "MEDiffraction.h"
#include "ThePEG/Utilities/DescribeClass.h"
#include "ThePEG/Interface/ClassDocumentation.h"
#include "ThePEG/Interface/Reference.h"
#include "ThePEG/Utilities/SimplePhaseSpace.h"
#include "ThePEG/Repository/EventGenerator.h"
#include "ThePEG/Handlers/StandardXComb.h"
#include "ThePEG/Handlers/SamplerBase.h"
#include "ThePEG/Persistency/PersistentOStream.h"
#include "ThePEG/Persistency/PersistentIStream.h"
using namespace Herwig;
#include "ThePEG/PDT/EnumParticles.h"
#include "ThePEG/MatrixElement/Tree2toNDiagram.h"
#include "ThePEG/Interface/Parameter.h"
#include "ThePEG/Interface/Switch.h"
#include "Herwig/Utilities/Kinematics.h"
MEDiffraction::MEDiffraction()
: HwMEBase(),
deltaOnly(false),
isInRunPhase(false),
theProtonMass(-MeV) // to be set in doinit
{}
void MEDiffraction::getDiagrams() const {
//incoming particles
cPDPair incomingHardons = generator()->eventHandler()->incoming();
tcPDPtr pom = getParticleData(990);
//get incoming particles
tcPDPtr prt11 = getParticleData(incomingHardons.first->id());
tcPDPtr prt12 = getParticleData(incomingHardons.second->id());
//get sign of id
int sign1=0, sign2=0;
sign1 = (incomingHardons.first->id() > 0) ? 1 : -1;
sign2 = (incomingHardons.second->id() > 0) ? 1 : -1;
tcPDPtr prt21 = getParticleData(sign1*2214);//Delta+
tcPDPtr prt22 = getParticleData(sign2*2214);//Delta+
//for the left side
tcPDPtr q11 = getParticleData(sign1*2); //u
tcPDPtr q21 = getParticleData(sign1*1); //d
//for the right side
tcPDPtr q12 = getParticleData(sign2*2); //u
tcPDPtr q22 = getParticleData(sign2*1); //d
//for the left side
tcPDPtr dq11 = getParticleData(sign1*2101); //ud_0
tcPDPtr dq111 = getParticleData(sign1*2103); //ud_1
tcPDPtr dq21 = getParticleData(sign1*2203); //uu_1
//for the right side
tcPDPtr dq12 = getParticleData(sign2*2101); //ud_0
tcPDPtr dq112 = getParticleData(sign2*2103); //ud_1
tcPDPtr dq22 = getParticleData(sign2*2203); //uu_1
tcPDPtr gl = getParticleData(21);//gluon
//switch between dissociation decays to different
//number of clusters or dissociation into delta only
//(Maybe can be automated???)
//(Should be generalized to ppbar, for example!!!)
switch(dissociationDecay){
case 0: //one cluster or only delta in the final state
if(deltaOnly) //only delta in the final state
{
switch (diffDirection){
case 0:
add(new_ptr((Tree2toNDiagram(3), prt11, pom, prt12, 1, prt21, 2, prt12, -1)));
break;
case 1:
add(new_ptr((Tree2toNDiagram(3), prt11, pom, prt12, 1, prt11, 2, prt22, -1)));
break;
case 2:
add(new_ptr((Tree2toNDiagram(3), prt11, pom, prt12, 1, prt21, 2, prt22, -1)));
break;
}
}else
{
//switch between direction of dissociated proton for single diffraction or
//double diffraction
switch (diffDirection){
case 0: //left
//u -- ud_0
add(new_ptr((Tree2toNDiagram(4), prt11, q11, pom, prt12, 3, prt12, 1, dq11, 2, q11, -1)));
//d -- uu_1
add(new_ptr((Tree2toNDiagram(4), prt11, q21, pom, prt12, 3, prt12, 1, dq21, 2, q21, -2)));
break;
case 1: //right
//u -- ud_0
add(new_ptr((Tree2toNDiagram(4), prt11, pom, q12, prt12, 1, prt11, 3, dq12, 2, q12, -1)));
//d -- uu_1
add(new_ptr((Tree2toNDiagram(4), prt11, pom, q22, prt12, 1, prt11, 3, dq22, 2, q22, -2)));
break;
case 2: //double
//u -- ud_0 left u -- ud_0 right
add(new_ptr((Tree2toNDiagram(5), prt11, q11, pom, q12, prt12, 1, dq11, 2, q11, 3, q12, 4, dq12, -1)));
//u -- ud_0 left d -- uu_1 right
add(new_ptr((Tree2toNDiagram(5), prt11, q11, pom, q22, prt12, 1, dq11, 2, q11, 3, q22, 4, dq22, -2)));
//d -- uu_1 left u -- ud_0 right
add(new_ptr((Tree2toNDiagram(5), prt11, q21, pom, q12, prt12, 1,dq21, 2, q21, 3, q12, 4, dq12, -3)));
//d -- uu_1 left d -- uu_1 right
add(new_ptr((Tree2toNDiagram(5), prt11, q21, pom, q22, prt12, 1, dq21, 2, q21, 3, q22, 4, dq22, -4)));
break;
}
}
break;
case 1: //two clusters (cases with ud_1 not included)
switch (diffDirection){
case 0: //left
//u -- ud_0
add(new_ptr((Tree2toNDiagram(5), prt11, q11, gl, pom, prt12, 1, dq11, 2, q11, 3, gl, 4, prt12, -1)));
//d -- uu_1
add(new_ptr((Tree2toNDiagram(5), prt11, q21, gl, pom, prt12, 1, dq21, 2, q21, 3, gl, 4, prt12, -2)));
break;
case 1: //right
//u -- ud_0
add(new_ptr((Tree2toNDiagram(5), prt11, pom, gl, q12, prt12, 1, prt11, 2, gl, 3, q12, 4, dq12, -1)));
//d -- ud_1
add(new_ptr((Tree2toNDiagram(5), prt11, pom, gl, q22, prt12, 1, prt11, 2, gl, 3, q22, 4, dq22, -2)));
break;
case 2: //double
//u -- ud_0 left u -- ud_0 right
add(new_ptr((Tree2toNDiagram(7), prt11, q11, gl, pom, gl, q12, prt12, 1, dq11, 2, q11, 3, gl, 4,
gl, 5, q12, 6, dq12, -1)));
//u -- ud_0 left d -- uu_1 right
add(new_ptr((Tree2toNDiagram(7), prt11, q11, gl, pom, gl, q22, prt12, 1, dq11, 2, q11, 3, gl, 4,
gl, 5, q22, 6, dq22, -2)));
//d -- uu_1 left u -- ud_0 right
add(new_ptr((Tree2toNDiagram(7), prt11, q21, gl, pom, gl, q12, prt12, 1, dq21, 2, q21, 3, gl, 4,
gl, 5, q12, 6, dq12, -3)));
//d -- uu_1 left d -- uu_1 right
add(new_ptr((Tree2toNDiagram(7), prt11, q21, gl, pom, gl, q22, prt12, 1, dq21, 2, q21, 3, gl, 4,
gl, 5, q22, 6, dq22, -4)));
break;
}
break;
}
}
Energy2 MEDiffraction::scale() const {
return sqr(10*GeV);
}
int MEDiffraction::nDim() const {
return 0;
}
void MEDiffraction::setKinematics() {
HwMEBase::setKinematics(); // Always call the base class method first
}
bool MEDiffraction::generateKinematics(const double * ) {
// generate the masses of the particles
for (size_t i = 2; i < meMomenta().size(); ++i)
meMomenta()[i] = Lorentz5Momentum(mePartonData()[i]->generateMass());
/* sample M12, M22 and t, characterizing the diffractive final state */
const pair<pair<Energy2,Energy2>,Energy2> point = diffractiveMassAndMomentumTransfer();
const Energy2 M12 (point.first.first);
const Energy2 M22 (point.first.second);
const Energy2 t(point.second);
/* construct the hadronic momenta in the lab frame */
const double phi = UseRandom::rnd() * Constants::twopi;
const Energy cmEnergy = generator()->maximumCMEnergy();
const Energy2 s = sqr(cmEnergy);
//proton mass
const Energy2 m2 = sqr( theProtonMass );
const Energy E3 = (s - M22 + M12) / (2.*cmEnergy);
const Energy E4 = (s + M22 - M12) / (2.*cmEnergy);
//Momentum of outgoing proton and dissociated proton
const Energy pprime = sqrt(kallen(s, M12, M22)) / (2.*cmEnergy);
//costheta of scattering angle
double costheta = s*(s + 2*t - 2*m2 - M12 - M22)
/ sqrt( kallen(s, M12, M22)*kallen(s, m2, m2) );
assert(abs(costheta)<=1.);
const Energy pzprime = pprime*costheta;
const Energy pperp = pprime*sqrt(1 - sqr(costheta));
/* momenta in the lab frame */
const Lorentz5Momentum p3 = Lorentz5Momentum(pperp*cos(phi), pperp*sin(phi), pzprime, E3);
const Lorentz5Momentum p4 = Lorentz5Momentum(-pperp*cos(phi), -pperp*sin(phi), -pzprime, E4);
/* decay dissociated proton into quark-diquark */
//squares of constituent masses of quark and diquark
const Energy2 mq2(sqr(mq()));
Energy2 Mx2;
switch(diffDirection){
case 0:
Mx2=M12;
break;
case 1:
Mx2=M22;
break;
}
/* Select between left/right single diffraction and double diffraction */
//check if we want only delta for the excited state
//pair of momenta for double decay for a two cluster case
pair<Lorentz5Momentum,Lorentz5Momentum> momPair, momPair1;
//fraction of momenta
double frac = UseRandom::rnd();
switch(dissociationDecay){
case 0:
if(!deltaOnly) {
pair<Lorentz5Momentum,Lorentz5Momentum> decayMomenta;
pair<Lorentz5Momentum,Lorentz5Momentum> decayMomentaTwo;
//absolute collinear dissociation of the hadron
const double phiprime = phi;
//aligned with outgoing dissociated proton
const double costhetaprime = costheta;
const double sinthetaprime=sqrt(1-sqr(costhetaprime));
//axis along which diquark from associated proton is aligned
Axis dir = Axis(sinthetaprime*cos(phiprime), sinthetaprime*sin(phiprime), costhetaprime);
switch (diffDirection){
case 0://Left single diffraction
meMomenta()[4].setT(sqrt(mq2+sqr(meMomenta()[4].x())+sqr(meMomenta()[4].y())+sqr(meMomenta()[4].z())));
////////////////////////////////////////////////////
do{}
while(!Kinematics::twoBodyDecay(p3,mqq(),mq(),-dir,decayMomenta.first,decayMomenta.second));
///////////
meMomenta()[2] = p4;
meMomenta()[3] = decayMomenta. first;
meMomenta()[4] = decayMomenta.second;
break;
case 1://Right single diffraction
meMomenta()[4].setT(sqrt(mq2+sqr(meMomenta()[4].x())+sqr(meMomenta()[4].y())+sqr(meMomenta()[4].z())));
////////////////////////////////////////////////////
do{}
while(!Kinematics::twoBodyDecay(p4,mqq(),mq(),dir,decayMomenta.first,decayMomenta.second));
meMomenta()[2] = p3;
meMomenta()[3] = decayMomenta. first;
meMomenta()[4] = decayMomenta.second;
break;
case 2://double diffraction
do{}
while(!Kinematics::twoBodyDecay(p3,mqq(),mq(),-dir,decayMomenta.first,decayMomenta.second));
do{}
while(!Kinematics::twoBodyDecay(p4,mqq(),mq(),dir,decayMomentaTwo.first,decayMomentaTwo.second));
meMomenta()[2] = decayMomenta. first;
meMomenta()[3] = decayMomenta.second;
meMomenta()[4] = decayMomentaTwo.second;
meMomenta()[5] = decayMomentaTwo. first;
break;
}
}
else {
meMomenta()[2] = p3;
meMomenta()[3] = p4;
}
break;
case 1:
switch(diffDirection){
case 0:
//quark and diquark masses
meMomenta()[2].setMass(mqq());
meMomenta()[3].setMass(mq());
//gluon constituent mass
meMomenta()[4].setMass(getParticleData(21)->constituentMass());
//outgoing proton
meMomenta()[5].setVect(p4.vect());
meMomenta()[5].setT(p4.t());
//two body decay of the outgoing dissociation proton
do{}
while(!Kinematics::twoBodyDecay(p3,mqq()+mq(),getParticleData(21)->constituentMass(),
p3.vect().unit(),momPair.first,momPair.second));
//put gluon back-to-back with quark-diquark
//set momenta of quark and diquark
frac = mqq()/(mqq()+mq());
meMomenta()[2].setVect(frac*momPair.first.vect());
meMomenta()[2].setT(sqrt(sqr(frac)*momPair.first.vect().mag2()+sqr(mqq())));
meMomenta()[3].setVect((1-frac)*momPair.first.vect());
meMomenta()[3].setT(sqrt(sqr(1-frac)*momPair.first.vect().mag2()+sqr(mq())));
//set momentum of gluon
meMomenta()[4].setVect(momPair.second.vect());
meMomenta()[4].setT(momPair.second.t());
break;
case 1:
//quark and diquark masses
meMomenta()[5].setMass(mqq());
meMomenta()[4].setMass(mq());
//gluon constituent mass
meMomenta()[3].setMass(getParticleData(21)->constituentMass());
//outgoing proton
meMomenta()[2].setVect(p3.vect());
meMomenta()[2].setT(p3.t());
//two body decay of the outgoing dissociation proton
do{}
while(!Kinematics::twoBodyDecay(p4,mqq()+mq(),getParticleData(21)->constituentMass(),
p4.vect().unit(),momPair.first,momPair.second));
//put gluon back-to-back with quark-diquark
//set momenta of quark and diquark
frac = mqq()/(mqq()+mq());
meMomenta()[5].setVect(frac*momPair.first.vect());
meMomenta()[5].setT(sqrt(sqr(frac)*momPair.first.vect().mag2()+sqr(mqq())));
meMomenta()[4].setVect((1-frac)*momPair.first.vect());
meMomenta()[4].setT(sqrt(sqr(1-frac)*momPair.first.vect().mag2()+sqr(mq())));
//set momentum of gluon
meMomenta()[3].setVect(momPair.second.vect());
meMomenta()[3].setT(momPair.second.t());
break;
case 2:
//first dissociated proton constituents
meMomenta()[2].setMass(mqq());
meMomenta()[3].setMass(mq());
meMomenta()[4].setMass(getParticleData(21)->constituentMass());
//second dissociated proton constituents
meMomenta()[5].setMass(getParticleData(21)->constituentMass());
meMomenta()[6].setMass(mq());
meMomenta()[7].setMass(mqq());
//two body decay of the outgoing dissociation proton
do{}
while(!Kinematics::twoBodyDecay(p3,mqq()+mq(),getParticleData(21)->constituentMass(),
p3.vect().unit(),momPair.first,momPair.second));
do{}
while(!Kinematics::twoBodyDecay(p4,mqq()+mq(),getParticleData(21)->constituentMass(),
p4.vect().unit(),momPair1.first,momPair1.second));
//put gluon back-to-back with quark-diquark
frac = mqq()/(mqq()+mq());
//first dissociated proton
//set momenta of quark and diquark
meMomenta()[2].setVect(frac*momPair.first.vect());
meMomenta()[2].setT(sqrt(sqr(frac)*momPair.first.vect().mag2()+sqr(mqq())));
meMomenta()[3].setVect((1-frac)*momPair.first.vect());
meMomenta()[3].setT(sqrt(sqr(1-frac)*momPair.first.vect().mag2()+sqr(mq())));
//set momentum of gluon
meMomenta()[4].setVect(momPair.second.vect());
meMomenta()[4].setT(momPair.second.t());
//first dissociated proton
//set momenta of quark and diquark
meMomenta()[7].setVect(frac*momPair1.first.vect());
meMomenta()[7].setT(sqrt(sqr(frac)*momPair1.first.vect().mag2()+sqr(mqq())));
meMomenta()[6].setVect((1-frac)*momPair1.first.vect());
meMomenta()[6].setT(sqrt(sqr(1-frac)*momPair1.first.vect().mag2()+sqr(mq())));
//set momentum of gluon
meMomenta()[5].setVect(momPair1.second.vect());
meMomenta()[5].setT(momPair1.second.t());
break;
}
meMomenta()[2].rescaleEnergy();
meMomenta()[3].rescaleEnergy();
meMomenta()[4].rescaleEnergy();
meMomenta()[5].rescaleEnergy();
if(diffDirection==2){
meMomenta()[6].rescaleEnergy();
meMomenta()[7].rescaleEnergy();
}
break;
}
jacobian(sqr(cmEnergy)/GeV2);
return true;
}
//Generate masses of dissociated protons and momentum transfer from probability f(M2,t)
//(for single diffraction). Sample according to f(M2,t)=f(M2)f(t|M2).
pair<pair<Energy2,Energy2>,Energy2> MEDiffraction::diffractiveMassAndMomentumTransfer() const {
Energy2 theM12(ZERO),theM22(ZERO), thet(ZERO);
//proton mass squared
const Energy2 m2 = sqr(theProtonMass);
//delta mass squared
const Energy2 md2 = sqr(getParticleData(2214)->mass());
Energy2 M2;
bool condition = true;
do {
//check if we want only delta
if(deltaOnly) {
switch(diffDirection){
case 0:
theM12 = md2;
theM22 = m2;
M2 = md2;
if(generator()->maximumCMEnergy()<sqrt(theM12)+sqrt(theM22)) {
continue;
}
thet = randomt(md2);
break;
case 1:
theM22 = md2;
theM12 = m2;
M2 = md2;
if(generator()->maximumCMEnergy()<sqrt(theM12)+sqrt(theM22)) {
continue;
}
thet = randomt(md2);
break;
case 2:
theM12 = md2;
theM22 = md2;
M2 = md2;
if(generator()->maximumCMEnergy()<sqrt(theM12)+sqrt(theM22)) {
continue;
}
thet = doublediffrandomt(theM12,theM22);
break;
}
}
else {
switch (diffDirection){
case 0:
M2=randomM2();
theM12=M2;
theM22=m2;
if(generator()->maximumCMEnergy()<sqrt(theM12)+sqrt(theM22)) {
continue;
}
thet = randomt(M2);
break;
case 1:
theM12=m2;
M2=randomM2();
theM22=M2;
if(generator()->maximumCMEnergy()<sqrt(theM12)+sqrt(theM22)) {
continue;
}
thet = randomt(M2);
break;
case 2:
theM12=randomM2();
theM22=randomM2();
M2=(theM12>theM22) ? theM12: theM22;
if(generator()->maximumCMEnergy()<sqrt(theM12)+sqrt(theM22)) {
continue;
}
thet = doublediffrandomt(theM12,theM22);
break;
}
}
const Energy cmEnergy = generator()->maximumCMEnergy();
const Energy2 s = sqr(cmEnergy);
if(generator()->maximumCMEnergy()<sqrt(theM12)+sqrt(theM22)) {
condition = true;
continue;
}
InvEnergy2 slope;
if(diffDirection==2)
slope = 2*softPomeronSlope()*log(.1+(sqr(cmEnergy)/softPomeronSlope())/(theM12*theM22));
else
slope = protonPomeronSlope() + 2*softPomeronSlope()*log(sqr(cmEnergy)/M2);
if(theM12*theM22 >= sqr(cmEnergy)/softPomeronSlope()) {
condition = true;
continue;
}
const double expmax = exp(slope*tmaxfun(s,m2,M2));
const double expmin = exp(slope*tminfun(s,m2,M2));
// without (1-M2/s) constraint
condition = (UseRandom::rnd() > protonPomeronSlope()*(expmax-expmin)/slope );
}
while(condition);
return make_pair (make_pair(theM12,theM22),thet);
}
//Decay of the excited proton to quark-diquark
pair<Lorentz5Momentum,Lorentz5Momentum> MEDiffraction::twoBodyDecayMomenta(Lorentz5Momentum pp) const{
//Decay of the excited proton
const Energy2 Mx2(sqr(pp.mass())),mq2(sqr(mq())),mqq2(sqr(mqq()));
const Energy2 psq = ((Mx2-sqr(mq()+mqq()))*(Mx2-sqr(mq()-mqq())))/(4*Mx2);
assert(psq/GeV2>0);
const Energy p(sqrt(psq));
const double phi = UseRandom::rnd() * Constants::twopi;
const double costheta =1-2*UseRandom::rnd();
const double sintheta = sqrt(1-sqr(costheta));
Lorentz5Momentum k1=Lorentz5Momentum(p*sintheta*cos(phi), p*sintheta*sin(phi), p*costheta, sqrt(mq2+psq));
Lorentz5Momentum k2=Lorentz5Momentum(-p*sintheta*cos(phi), -p*sintheta*sin(phi), -p*costheta,sqrt(mqq2+psq));
//find boost to pp center of mass
const Boost betap3 = (pp).findBoostToCM();
//k1 and k2 calculated at p3 center of mass, so boost back
k1.boost(-betap3);
k2.boost(-betap3);
//first is quark, second diquark
return make_pair(k1,k2);
}
Energy2 MEDiffraction::randomt(Energy2 M2) const {
assert(protonPomeronSlope()*GeV2 > 0);
//proton mass
const Energy2 m2 = sqr( theProtonMass );
const Energy cmEnergy = generator()->maximumCMEnergy();
const Energy2 ttmin = tminfun(sqr(cmEnergy),m2,M2);
const Energy2 ttmax = tmaxfun(sqr(cmEnergy),m2,M2);
const InvEnergy2 slope = protonPomeronSlope()
+ 2*softPomeronSlope()*log(sqr(cmEnergy)/M2);
double r = UseRandom::rnd();
Energy2 newVal;
if(slope*ttmax>slope*ttmin) {
newVal = ttmax + log( r + (1.-r)*exp(slope*(ttmin-ttmax)) ) / slope;
}
else {
newVal = ttmin + log( 1. - r + r*exp(slope*(ttmax-ttmin))) / slope;
}
return newVal;
}
Energy2 MEDiffraction::doublediffrandomt(Energy2 M12, Energy2 M22) const {
const Energy cmEnergy = generator()->maximumCMEnergy();
const double shift = 0.1;
const InvEnergy2 slope = 2*softPomeronSlope()*log(shift+(sqr(cmEnergy)/softPomeronSlope())/(M12*M22));
const Energy2 ttmin = tminfun(sqr(cmEnergy),M12,M22);
const Energy2 ttmax = tmaxfun(sqr(cmEnergy),M12,M22);
double r = UseRandom::rnd();
Energy2 newVal;
if(slope*ttmax>slope*ttmin) {
newVal = ttmax + log( r + (1.-r)*exp(slope*(ttmin-ttmax)) ) / slope;
}
else {
newVal = ttmin + log( 1. - r + r*exp(slope*(ttmax-ttmin))) / slope;
}
return newVal;
}
Energy2 MEDiffraction::randomM2() const {
const double tmp = 1 - softPomeronIntercept();
const Energy cmEnergy = generator()->maximumCMEnergy();
return sqr(cmEnergy) * pow( pow(M2min()/sqr(cmEnergy),tmp) +
UseRandom::rnd() * (pow(M2max()/sqr(cmEnergy),tmp) - pow(M2min()/sqr(cmEnergy),tmp)),
1.0/tmp );
}
Energy2 MEDiffraction::tminfun(Energy2 s, Energy2 M12, Energy2 M22) const {
const Energy2 m2 = sqr( theProtonMass );
return 0.5/s*(-sqrt(kallen(s, m2, m2)*kallen(s, M12, M22))-sqr(s)+2*s*m2+s*M12+s*M22);
}
Energy2 MEDiffraction::tmaxfun(Energy2 s, Energy2 M12, Energy2 M22) const {
const Energy2 m2 = sqr( theProtonMass );
return 0.5/s*(sqrt(kallen(s, m2, m2)*kallen(s, M12, M22))-sqr(s)+2*s*m2+s*M12+s*M22);
}
double MEDiffraction::correctionweight() const {
// Here we calculate the weight to restore the diffractiveXSec
// given by the MPIHandler.
// First get the eventhandler to get the current cross sections.
static Ptr<StandardEventHandler>::tptr eh =
dynamic_ptr_cast<Ptr<StandardEventHandler>::tptr>(generator()->eventHandler());
// All diffractive processes make use of this ME.
// The static map can be used to collect all the sumOfWeights.
static map<XCombPtr,double> weightsmap;
weightsmap[lastXCombPtr()]=lastXComb().stats().sumWeights();
// Define static variable to keep trac of reweighting
static double rew_=1.;
static int countUpdateWeight=50;
static double sumRew=0.;
static double countN=0;
// if we produce events we count
if(eh->integratedXSec()>ZERO)sumRew+=rew_;
if(eh->integratedXSec()>ZERO)countN+=1.;
if(countUpdateWeight<countN){
// Summing all diffractive processes (various initial states)
double sum=0.;
for(auto xx:weightsmap){
sum+=xx.second;
}
double avRew=sumRew/countN;
CrossSection XS_have =eh->sampler()->maxXSec()/eh->sampler()->attempts()*sum;
CrossSection XS_wanted=MPIHandler_->diffractiveXSec();
double deltaN=50;
// Cross section without reweighting: XS_norew
// XS_have = avcsNorm2*XS_norew (for large N)
// We want to determine the rew that allows to get the wanted XS.
// In deltaN points we want (left) and we get (right):
// XS_wanted*(countN+deltaN) = XS_have*countN + rew*deltaN*XS_norew
// Solve for rew:
rew_=avRew*(XS_wanted*(countN+deltaN)-XS_have*countN)/(XS_have*deltaN);
countUpdateWeight+=deltaN;
}
//Make sure we dont produce negative weights.
// TODO: write finalize method that checks if reweighting was performed correctly.
rew_=max(rew_,0.000001);
rew_=min(rew_,10000.0);
return rew_;
}
double MEDiffraction::me2() const{
return theme2;
}
CrossSection MEDiffraction::dSigHatDR() const {
// If we only have single diffraction turned on, then the correctionweight()
// will give odd and undetermined results.
if (singleDiffractionOnly){
return me2()*jacobian()/sHat()*sqr(hbarc);
}
else return me2()*jacobian()/sHat()*sqr(hbarc)*correctionweight();
}
unsigned int MEDiffraction::orderInAlphaS() const {
return 0;
}
unsigned int MEDiffraction::orderInAlphaEW() const {
return 0;
}
Selector<MEBase::DiagramIndex>
MEDiffraction::diagrams(const DiagramVector & diags) const {
Selector<DiagramIndex> sel;
if(!deltaOnly){
if(diffDirection<2){
for(unsigned int i = 0; i < diags.size(); i++){
if(diags[0]->id()==-1)
sel.insert(2./3.,i);
else
sel.insert(1./3.,i);
}
}else{
for(unsigned int i = 0; i < diags.size(); i++){
if(diags[0]->id()==-1)
sel.insert(4./9.,i);
else if(diags[0]->id()==-2)
sel.insert(2./9.,i);
else if(diags[0]->id()==-3)
sel.insert(2./9.,i);
else
sel.insert(1./9.,i);
}
}
}else{
sel.insert(1.0,0);
}
return sel;
}
Selector<const ColourLines *>
MEDiffraction::colourGeometries(tcDiagPtr ) const {
Selector<const ColourLines *> sel;
int sign1=0, sign2=0;
sign1 = (generator()->eventHandler()->incoming().first->id() > 0) ? 1 : -1;
sign2 = (generator()->eventHandler()->incoming().second->id() > 0) ? 1 : -1;
switch(dissociationDecay){
case 0:
if(!deltaOnly)
{
if(diffDirection!=2){
if (diffDirection == 0){
if(sign1>0){
static ColourLines dqq0=ColourLines("-6 2 7");
sel.insert(1.0,&dqq0);
}else{
static ColourLines dqq0=ColourLines("6 -2 -7");
sel.insert(1.0,&dqq0);
}
}
else{
if(sign2>0){
static ColourLines dqq1=ColourLines("-6 3 7");
sel.insert(1.0,&dqq1);
}else{
static ColourLines dqq1=ColourLines("6 -3 -7");
sel.insert(1.0,&dqq1);
}
}
}else{
if(sign1>0 && sign2>0){
static ColourLines ddqq0=ColourLines("-6 2 7, -9 4 8");
sel.insert(1.0,&ddqq0);
}else if(sign1<0 && sign2>0){
static ColourLines ddqq0=ColourLines("6 -2 -7, -9 4 8");
sel.insert(1.0,&ddqq0);
}else if(sign1>0&& sign2<0){
static ColourLines ddqq0=ColourLines("-6 2 7, 9 -4 -8");
sel.insert(1.0,&ddqq0);
}else{
static ColourLines ddqq0=ColourLines("6 -2 -7, 9 -4 -8");
sel.insert(1.0,&ddqq0);
}
}
}else
{
static ColourLines cl("");
sel.insert(1.0, &cl);
}
break;
case 1:
switch(diffDirection){
case 0:
static ColourLines clleft("-6 2 3 8, -8 -3 7");
sel.insert(1.0, &clleft);
break;
case 1:
static ColourLines clright("-9 4 3 7, -7 -3 8");
sel.insert(1.0, &clright);
break;
case 2:
static ColourLines cldouble("-8 2 3 10, -10 -3 9, -13 6 5 11, -11 -5 12");
sel.insert(1.0, &cldouble);
break;
}
break;
}
return sel;
}
void MEDiffraction::doinit() {
HwMEBase::doinit();
theProtonMass = getParticleData(2212)->mass();
}
void MEDiffraction::doinitrun() {
HwMEBase::doinitrun();
isInRunPhase = true;
}
IBPtr MEDiffraction::clone() const {
return new_ptr(*this);
}
IBPtr MEDiffraction::fullclone() const {
return new_ptr(*this);
}
// The following static variable is needed for the type
// description system in ThePEG.
DescribeClass<MEDiffraction,HwMEBase>
describeHerwigMEDiffraction("Herwig::MEDiffraction", "HwMEHadron.so");
void MEDiffraction::persistentOutput(PersistentOStream & os) const {
os << theme2 << deltaOnly << diffDirection << theprotonPomeronSlope
<< thesoftPomeronIntercept << thesoftPomeronSlope << dissociationDecay
<< ounit(theProtonMass,GeV) << MPIHandler_ << singleDiffractionOnly;
}
void MEDiffraction::persistentInput(PersistentIStream & is, int) {
is >> theme2 >> deltaOnly >> diffDirection >> theprotonPomeronSlope
>> thesoftPomeronIntercept >> thesoftPomeronSlope >> dissociationDecay
>> iunit(theProtonMass,GeV)>> MPIHandler_ >> singleDiffractionOnly;
}
InvEnergy2 MEDiffraction::protonPomeronSlope() const{
return theprotonPomeronSlope/GeV2;
}
double MEDiffraction::softPomeronIntercept() const {
return thesoftPomeronIntercept;
}
InvEnergy2 MEDiffraction::softPomeronSlope() const {
return thesoftPomeronSlope/GeV2;
}
void MEDiffraction::Init() {
static ClassDocumentation<MEDiffraction> documentation
("There is no documentation for the MEDiffraction class");
static Parameter<MEDiffraction,double> interfaceme2
("DiffractionAmplitude",
"The square of the diffraction amplitude used to determine the "
"cross section.",
&MEDiffraction::theme2, 1.0, 0.00001, 100.0,
false, false, Interface::limited);
static Parameter<MEDiffraction,double> interfaceprotonPomeronSlope
("ProtonPomeronSlope",
"The proton-pomeron slope parameter.",
&MEDiffraction::theprotonPomeronSlope, 10.1, 0.00001, 100.0,
false, false, Interface::limited);
static Parameter<MEDiffraction,double> interfacesoftPomeronIntercept
("SoftPomeronIntercept",
"The soft pomeron intercept.",
&MEDiffraction::thesoftPomeronIntercept, 1.08, 0.00001, 100.0,
false, false, Interface::limited);
static Parameter<MEDiffraction,double> interfacesoftPomeronSlope
("SoftPomeronSlope",
"The soft pomeron slope parameter.",
&MEDiffraction::thesoftPomeronSlope, 0.25, 0.00001, 100.0,
false, false, Interface::limited);
static Switch<MEDiffraction, bool> interfaceDeltaOnly
("DeltaOnly",
"proton-proton to proton-delta only",
&MEDiffraction::deltaOnly, 0, false, false);
static SwitchOption interfaceDeltaOnly0
(interfaceDeltaOnly,"No","Final state with Delta only is OFF", 0);
static SwitchOption interfaceDeltaOnly1
(interfaceDeltaOnly,"Yes","Final state with Delta only is ON", 1);
//Select if the left, right or both protons are excited
static Switch<MEDiffraction, unsigned int> interfaceDiffDirection
("DiffDirection",
"Direction of the excited proton",
&MEDiffraction::diffDirection, 0, false, false);
static SwitchOption left
(interfaceDiffDirection,"Left","Proton moving in the positive z direction", 0);
static SwitchOption right
(interfaceDiffDirection,"Right","Proton moving in the negative z direction", 1);
static SwitchOption both
(interfaceDiffDirection,"Both","Both protons", 2);
//Select if two or three body decay
static Switch<MEDiffraction, unsigned int> interfaceDissociationDecay
("DissociationDecay",
"Number of clusters the dissociated proton decays",
&MEDiffraction::dissociationDecay, 0, false, false);
static SwitchOption one
(interfaceDissociationDecay,"One","Dissociated proton decays into one cluster", 0);
static SwitchOption two
(interfaceDissociationDecay,"Two","Dissociated proton decays into two clusters", 1);
static Reference<MEDiffraction,UEBase> interfaceMPIHandler
("MPIHandler",
"The object that administers all additional scatterings.",
&MEDiffraction::MPIHandler_, false, false, true, true);
static Switch<MEDiffraction, bool> interfaceSingleDiffractionOnly
("SingleDiffractionOnly",
"Only allow single diffraction to occur in diffractive events",
&MEDiffraction::singleDiffractionOnly, 0, false, false);
static SwitchOption interfaceSingleDiffractionOnly0
(interfaceSingleDiffractionOnly,"No","Single-diffractive events only is OFF", 0);
static SwitchOption interfaceSingleDiffractionOnly1
(interfaceSingleDiffractionOnly,"Yes","Single-diffractive events only is ON", 1);
}

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