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// RHadrons.cc is a part of the PYTHIA event generator.
// Copyright (C) 2012 Torbjorn Sjostrand.
// PYTHIA is licenced under the GNU GPL version 2, see COPYING for details.
// Please respect the MCnet Guidelines, see GUIDELINES for details.
// Function definitions (not found in the header) for the RHadrons class.
#include "RHadrons.h"
namespace Pythia8 {
//==========================================================================
// The RHadrons class.
//--------------------------------------------------------------------------
// Constants: could be changed here if desired, but normally should not.
// These are of technical nature, as described for each.
const int RHadrons::IDRHADSB[14] = { 1000512, 1000522, 1000532,
1000542, 1000552, 1005113, 1005211, 1005213, 1005223, 1005311,
1005313, 1005321, 1005323, 1005333 };
const int RHadrons::IDRHADST[14] = { 1000612, 1000622, 1000632,
1000642, 1000652, 1006113, 1006211, 1006213, 1006223, 1006311,
1006313, 1006321, 1006323, 1006333 };
// Gluino code and list of gluino R-hadron codes.
const int RHadrons::IDRHADGO[38] = { 1000993, 1009113, 1009213,
1009223, 1009313, 1009323, 1009333, 1009413, 1009423, 1009433,
1009443, 1009513, 1009523, 1009533, 1009543, 1009553, 1091114,
1092114, 1092214, 1092224, 1093114, 1093214, 1093224, 1093314,
1093324, 1093334, 1094114, 1094214, 1094224, 1094314, 1094324,
1094334, 1095114, 1095214, 1095224, 1095314, 1095324, 1095334 };
// Allow a few tries for flavour selection since failure is allowed.
const int RHadrons::NTRYMAX = 10;
// Safety margin (in GeV) when constructing kinematics of system.
const double RHadrons::MSAFETY = 0.1;
// Maximal energy to borrow for gluon to insert on leg in to junction.
const double RHadrons::EGBORROWMAX = 4.;
//--------------------------------------------------------------------------
// Main routine to initialize R-hadron handling.
bool RHadrons::init( Info* infoPtrIn, Settings& settings,
ParticleData* particleDataPtrIn, Rndm* rndmPtrIn) {
// Store input pointers for future use.
infoPtr = infoPtrIn;
particleDataPtr = particleDataPtrIn;
rndmPtr = rndmPtrIn;
// Flags and parameters related to R-hadron formation and decay.
allowRH = settings.flag("RHadrons:allow");
maxWidthRH = settings.parm("RHadrons:maxWidth");
idRSb = settings.mode("RHadrons:idSbottom");
idRSt = settings.mode("RHadrons:idStop");
idRGo = settings.mode("RHadrons:idGluino");
setMassesRH = settings.flag("RHadrons:setMasses");
probGluinoballRH = settings.parm("RHadrons:probGluinoball");
mOffsetCloudRH = settings.parm("RHadrons:mOffsetCloud");
mCollapseRH = settings.parm("RHadrons:mCollapse");
diquarkSpin1RH = settings.parm("RHadrons:diquarkSpin1");
// Check whether sbottom, stop or gluino should form R-hadrons.
allowRSb = allowRH && idRSb > 0
&& (particleDataPtr->mWidth(idRSb) < maxWidthRH);
allowRSt = allowRH && idRSt > 0
&& (particleDataPtr->mWidth(idRSt) < maxWidthRH);
allowRGo = allowRH && idRGo > 0
&& (particleDataPtr->mWidth(idRGo) < maxWidthRH);
allowSomeR = allowRSb || allowRSt || allowRGo;
// Set nominal masses of sbottom R-mesons and R-baryons.
if (allowRSb) {
m0Sb = particleDataPtr->m0(idRSb);
if (setMassesRH) {
for (int i = 0; i < 14; ++i) {
int idR = IDRHADSB[i];
double m0RHad = m0Sb + mOffsetCloudRH;
m0RHad += particleDataPtr->constituentMass( (idR%100)/10);
if (i > 4)
m0RHad += particleDataPtr->constituentMass( (idR%1000)/100 );
particleDataPtr->m0( idR, m0RHad);
}
}
// Set widths and lifetimes of sbottom R-hadrons.
double mWidthRHad = particleDataPtr->mWidth(idRSb);
double tau0RHad = particleDataPtr->tau0( idRSb);
for (int i = 0; i < 14; ++i) {
particleDataPtr->mWidth( IDRHADSB[i], mWidthRHad);
particleDataPtr->tau0( IDRHADSB[i], tau0RHad);
}
}
// Set nominal masses of stop R-mesons and R-baryons.
if (allowRSt) {
m0St = particleDataPtr->m0(idRSt);
if (setMassesRH) {
for (int i = 0; i < 14; ++i) {
int idR = IDRHADST[i];
double m0RHad = m0St + mOffsetCloudRH;
m0RHad += particleDataPtr->constituentMass( (idR%100)/10);
if (i > 4)
m0RHad += particleDataPtr->constituentMass( (idR%1000)/100 );
particleDataPtr->m0( idR, m0RHad);
}
}
// Set widths and lifetimes of stop R-hadrons.
double mWidthRHad = particleDataPtr->mWidth(idRSt);
double tau0RHad = particleDataPtr->tau0( idRSt);
for (int i = 0; i < 14; ++i) {
particleDataPtr->mWidth( IDRHADST[i], mWidthRHad);
particleDataPtr->tau0( IDRHADST[i], tau0RHad);
}
}
// Set nominal masses of gluino R-glueballs, R-mesons and R-baryons.
if (allowRGo) {
m0Go = particleDataPtr->m0(idRGo);
if (setMassesRH) {
particleDataPtr->m0( IDRHADGO[0], m0Go + 2. * mOffsetCloudRH
+ particleDataPtr->constituentMass(21) );
for (int i = 1; i < 38; ++i) {
int idR = IDRHADGO[i];
double m0RHad = m0Go + 2. * mOffsetCloudRH;
m0RHad += particleDataPtr->constituentMass( (idR%1000)/100 );
m0RHad += particleDataPtr->constituentMass( (idR%100)/10);
if (i > 15)
m0RHad += particleDataPtr->constituentMass( (idR%10000)/1000 );
particleDataPtr->m0( idR, m0RHad);
}
}
// Set widths and lifetimes of gluino R-hadrons.
double mWidthRHad = particleDataPtr->mWidth(idRGo);
double tau0RHad = particleDataPtr->tau0( idRGo);
for (int i = 0; i < 38; ++i) {
particleDataPtr->mWidth( IDRHADGO[i], mWidthRHad);
particleDataPtr->tau0( IDRHADGO[i], tau0RHad);
}
}
// Done.
return true;
}
//--------------------------------------------------------------------------
// Check if a given particle can produce R-hadrons.
bool RHadrons::givesRHadron( int id) {
if (allowRSb && abs(id) == idRSb) return true;
if (allowRSt && abs(id) == idRSt) return true;
if (allowRGo && id == idRGo) return true;
return false;
}
//--------------------------------------------------------------------------
// Produce R-hadrons by fragmenting them off from existing strings.
bool RHadrons::produce( ColConfig& colConfig, Event& event) {
// Check whether some sparticles are allowed to hadronize.
if (!allowSomeR) return true;
// Reset arrays and values.
iBefRHad.resize(0);
iCreRHad.resize(0);
iRHadron.resize(0);
iAftRHad.resize(0);
isTriplet.resize(0);
nRHad = 0;
// Loop over event and identify hadronizing sparticles.
for (int i = 0; i < event.size(); ++i)
if (event[i].isFinal() && givesRHadron(event[i].id())) {
iBefRHad.push_back(i);
iCreRHad.push_back(i);
iRHadron.push_back(0);
iAftRHad.push_back(0);
isTriplet.push_back(true);
}
nRHad = iRHadron.size();
// Done if no hadronizing sparticles.
if (nRHad == 0) return true;
// Max two R-hadrons. Randomize order of processing.
if (nRHad > 2) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"cannot handle more than two R-hadrons");
return false;
}
if (nRHad > 1 && rndmPtr->flat() > 0.5) swap( iBefRHad[0], iBefRHad[1]);
// Split a system with both a sparticle and a junction.
iBef = iBefRHad[0];
iSys = colConfig.findSinglet( iBef);
systemPtr = &colConfig[iSys];
if (systemPtr->hasJunction && !splitOffJunction( colConfig, event)) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"cannot handle system with junction");
return false;
}
if (nRHad == 2) {
iBef = iBefRHad[1];
iSys = colConfig.findSinglet( iBefRHad[1]);
systemPtr = &colConfig[iSys];
if (systemPtr->hasJunction && !splitOffJunction( colConfig, event)) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"cannot handle system with junction");
return false;
}
}
// Open up a closed gluon/gluino loop.
iBef = iBefRHad[0];
iSys = colConfig.findSinglet( iBef);
systemPtr = &colConfig[iSys];
if (systemPtr->isClosed && !openClosedLoop( colConfig, event)) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"cannot open up closed gluon/gluino loop");
return false;
}
if (nRHad == 2) {
iBef = iBefRHad[1];
iSys = colConfig.findSinglet( iBefRHad[1]);
systemPtr = &colConfig[iSys];
if (systemPtr->isClosed && !openClosedLoop( colConfig, event)) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"cannot open up closed gluon/gluino loop");
return false;
}
}
// Split up a colour singlet system that should give two R-hadrons.
if (nRHad == 2) {
int iSys1 = colConfig.findSinglet( iBefRHad[0]);
int iSys2 = colConfig.findSinglet( iBefRHad[1]);
if (iSys2 == iSys1) {
iSys = iSys1;
systemPtr = &colConfig[iSys];
if ( !splitSystem( colConfig, event) ) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"failed to handle two sparticles in same system");
return false;
}
}
}
// Loop over R-hadrons to be formed. Find its colour singlet system.
for (iRHad = 0; iRHad < nRHad; ++iRHad) {
iBef = iBefRHad[iRHad];
iSys = colConfig.findSinglet( iBef);
if (iSys < 0) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"sparticle not in any colour singlet");
return false;
}
systemPtr = &colConfig[iSys];
// For now don't handle systems involving junctions or loops.
if (systemPtr->hasJunction) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"cannot handle system with junction");
return false;
}
if (systemPtr->isClosed) {
infoPtr->errorMsg("Error in RHadrons::produce: "
"cannot handle closed colour loop");
return false;
}
// Handle formation of R-hadron separately for gluino and squark.
if (event[iBef].id() == idRGo) isTriplet[iRHad] = false;
bool formed = (isTriplet[iRHad]) ? produceSquark( colConfig, event)
: produceGluino( colConfig, event);
if (!formed) return false;
// End of loop over R-hadrons. Done.
}
return true;
}
//--------------------------------------------------------------------------
// Decay R-hadrons by resolving them into string systems and letting the
// heavy unstable particle decay as normal.
bool RHadrons::decay( Event& event) {
// Loop over R-hadrons to decay.
for (iRHad = 0; iRHad < nRHad; ++iRHad) {
int iRNow = iRHadron[iRHad];
int iRBef = iBefRHad[iRHad];
int idRHad = event[iRNow].id();
double mRHad = event[iRNow].m();
double mRBef = event[iRBef].m();
int iR0 = 0;
int iR2 = 0;
// Find flavour content of squark or gluino R-hadron.
pair<int,int> idPair = (isTriplet[iRHad])
? fromIdWithSquark( idRHad) : fromIdWithGluino( idRHad);
int id1 = idPair.first;
int id2 = idPair.second;
// Sharing of momentum: the squark/gluino should be restored
// to original mass, but error if negative-mass spectators.
double fracR = mRBef / mRHad;
if (fracR >= 1.) {
infoPtr->errorMsg("Error in RHadrons::decay: "
"too low R-hadron mass for decay");
return false;
}
// Squark: new colour needed in the breakup.
if (isTriplet[iRHad]) {
int colNew = event.nextColTag();
int col = (event[iRBef].col() != 0) ? colNew : 0;
int acol = (col == 0) ? colNew : 0;
// Store the constituents of a squark R-hadron.
iR0 = event.append( id1, 106, iRNow, 0, 0, 0, col, acol,
fracR * event[iRNow].p(), fracR * mRHad, 0.);
iR2 = event.append( id2, 106, iRNow, 0, 0, 0, acol, col,
(1. - fracR) * event[iRNow].p(), (1. - fracR) * mRHad, 0.);
// Gluino: set mass sharing between two spectators.
} else {
double m1Eff = particleDataPtr->constituentMass(id1) + mOffsetCloudRH;
double m2Eff = particleDataPtr->constituentMass(id2) + mOffsetCloudRH;
double frac1 = (1. - fracR) * m1Eff / ( m1Eff + m2Eff);
double frac2 = (1. - fracR) * m2Eff / ( m1Eff + m2Eff);
// Two new colours needed in the breakups.
int col1 = event.nextColTag();
int col2 = event.nextColTag();
// Store the constituents of a gluino R-hadron.
iR0 = event.append( idRGo, 106, iRNow, 0, 0, 0, col2, col1,
fracR * event[iRNow].p(), fracR * mRHad, 0.);
event.append( id1, 106, iRNow, 0, 0, 0, col1, 0,
frac1 * event[iRNow].p(), frac1 * mRHad, 0.);
iR2 = event.append( id2, 106, iRNow, 0, 0, 0, 0, col2,
frac2 * event[iRNow].p(), frac2 * mRHad, 0.);
}
// Mark R-hadron as decayed and update history.
event[iRNow].statusNeg();
event[iRNow].daughters( iR0, iR2);
iAftRHad[iRHad] = iR0;
// Set secondary vertex for decay products, but no lifetime.
Vec4 vDec = event[iRNow].vProd() + event[iRNow].tau()
* event[iR0].p() / event[iR0].m();
for (int iRd = iR0; iRd <= iR2; ++iRd) event[iRd].vProd( vDec);
// End loop over R-hadron decays, based on velocity of squark.
}
// Done.
return true;
}
//--------------------------------------------------------------------------
// Split a system that contains both a sparticle and a junction.
bool RHadrons::splitOffJunction( ColConfig& colConfig, Event& event) {
// Classify system into three legs, and find sparticle location.
vector<int> leg1, leg2, leg3;
int iLegSP = 0;
int iPosSP = 0;
int iLeg = 0;
int iPos = 0;
for (int i = 0; i < systemPtr->size(); ++i) {
++iPos;
int iP = systemPtr->iParton[i];
if (iP < 0) {
++iLeg;
iPos = -1;
} else if (iLeg == 1) leg1.push_back( iP);
else if (iLeg == 2) leg2.push_back( iP);
else if (iLeg == 3) leg3.push_back( iP);
if (iP == iBef) {
iLegSP = iLeg;
iPosSP = iPos;
}
}
if (iLegSP == 0) return false;
// Swap so leg 1 contains sparticle. If not innermost sparticle then
// skip for now, and wait for this other (gluino!) to be split off.
if (iLegSP == 2) swap(leg2, leg1);
else if (iLegSP == 3) swap(leg3, leg1);
for (int i = 0; i < iPosSP; ++i)
if (event[leg1[i]].id() != 21) return true;
// No gluon between sparticle and junction: find kinetic energy of system.
if (iPosSP == 0) {
Vec4 pSP = event[iBef].p();
Vec4 pRec = 0.;
for (int i = 0; i < int(leg2.size()); ++i) pRec += event[leg2[i]].p();
for (int i = 0; i < int(leg3.size()); ++i) pRec += event[leg3[i]].p();
double mSys = (pSP + pRec).mCalc();
double mSP = pSP.mCalc();
double mRec = pRec.mCalc();
double eKin = mSys - mSP - mRec;
// Insert new gluon that borrows part of kinetic energy.
double mNewG = EGBORROWMAX * eKin / (EGBORROWMAX + eKin) ;
Vec4 pNewG = (mNewG / mSys) * (pSP + pRec);
int newCol = event.nextColTag();
bool isCol = (event[leg1.back()].col() > 0);
int colNG = (isCol)? newCol : event[iBef].acol();
int acolNG = (isCol) ? event[iBef].col() : newCol;
int iNewG = event.append( 21, 101, iBef, 0, 0, 0, colNG, acolNG,
pNewG, mNewG, 0.);
leg1.insert( leg1.begin(), iNewG);
++iPosSP;
// Boosts for remainder systems that gave up energy.
double mNewSys = mSys - mNewG;
double pAbsOld = 0.5 * sqrtpos( pow2(mSys*mSys - mSP*mSP - mRec*mRec)
- pow2(2. * mSP * mRec) ) / mSys;
double pAbsNew = 0.5 * sqrtpos( pow2(mNewSys*mNewSys - mSP*mSP - mRec*mRec)
- pow2(2. * mSP * mRec) ) / mNewSys;
RotBstMatrix MtoCM, MfromCM, MSP, MRec;
MtoCM.toCMframe( pSP, pRec);
MfromCM = MtoCM;
MfromCM.invert();
MSP = MtoCM;
MSP.bst( 0., 0., -pAbsOld / sqrt(mSP * mSP + pAbsOld * pAbsOld));
MSP.bst( 0., 0., pAbsNew / sqrt(mSP * mSP + pAbsNew * pAbsNew));
MSP.rotbst( MfromCM);
MRec = MtoCM;
MRec.bst( 0., 0., pAbsOld / sqrt(mRec * mRec + pAbsOld * pAbsOld));
MRec.bst( 0., 0., -pAbsNew / sqrt(mRec * mRec + pAbsNew * pAbsNew));
MRec.rotbst( MfromCM);
// Copy down recoling partons and boost their momenta.
int iNewSP = event.copy( iBef, 101);
event[iNewSP].rotbst( MSP);
leg1[iPosSP] = iNewSP;
if (iBefRHad[0] == iBef) iBefRHad[0] = iNewSP;
else if (nRHad > 1 && iBefRHad[1] == iBef) iBefRHad[1] = iNewSP;
iBef = iNewSP;
for (int i = 0; i < int(leg2.size()); ++i) {
int iCopy = event.copy( leg2[i], 101);
event[iCopy].rotbst( MRec);
if (iBefRHad[0] == leg2[i]) iBefRHad[0] = iCopy;
else if (nRHad > 1 && iBefRHad[1] == leg2[i]) iBefRHad[1] = iCopy;
leg2[i] = iCopy;
}
for (int i = 0; i < int(leg3.size()); ++i) {
int iCopy = event.copy( leg3[i], 101);
event[iCopy].rotbst( MRec);
if (iBefRHad[0] == leg3[i]) iBefRHad[0] = iCopy;
else if (nRHad > 1 && iBefRHad[1] == leg3[i]) iBefRHad[1] = iCopy;
leg3[i] = iCopy;
}
// Now always at least one gluon between sparticle and junction.
}
// Find gluon with largest energy in sparticle rest frame.
int iGspl = 0;
double eGspl = event[leg1[0]].p() * event[iBef].p();
for (int i = 1; i < iPosSP; ++i) {
double eGnow = event[leg1[i]].p() * event[iBef].p();
if (eGnow > eGspl) {
iGspl = i;
eGspl = eGnow;
}
}
int iG = leg1[iGspl];
// Split this gluon into a collinear quark.antiquark pair.
int idNewQ = flavSelPtr->pickLightQ();
int iNewQ = event.append( idNewQ, 101, iG, 0, 0, 0, event[iG].col(), 0,
0.5 * event[iG].p(), 0.5 * event[iG].m(), 0.);
int iNewQb = event.append( -idNewQ, 101, iG, 0, 0, 0, 0, event[iG].acol(),
0.5 * event[iG].p(), 0.5 * event[iG].m(), 0.);
event[iG].statusNeg();
event[iG].daughters( iNewQ, iNewQb);
if (event[leg1.back()].col() == 0) swap( iNewQ, iNewQb);
// Collect two new systems after split.
vector<int> iNewSys1, iNewSys2;
iNewSys1.push_back( iNewQb);
for (int i = iGspl + 1; i < int(leg1.size()); ++i)
iNewSys1.push_back( leg1[i]);
iNewSys2.push_back( -10);
for (int i = 0; i < iGspl; ++i) iNewSys2.push_back( leg1[i]);
iNewSys2.push_back( iNewQ);
iNewSys2.push_back( -11);
for (int i = 0; i < int(leg2.size()); ++i) iNewSys2.push_back( leg2[i]);
iNewSys2.push_back( -12);
for (int i = 0; i < int(leg3.size()); ++i) iNewSys2.push_back( leg3[i]);
// Remove old system and insert two new ones.
colConfig.erase(iSys);
colConfig.insert( iNewSys1, event);
colConfig.insert( iNewSys2, event);
// Done.
return true;
}
//--------------------------------------------------------------------------
// Open up a closed gluon/gluino loop.
bool RHadrons::openClosedLoop( ColConfig& colConfig, Event& event) {
// Find gluon with largest energy in gluino rest frame.
int iGspl = -1;
double eGspl = 0.;
for (int i = 0; i < systemPtr->size(); ++i) {
int iGNow = systemPtr->iParton[i];
if (event[iGNow].id() == 21) {
double eGnow = event[iGNow].p() * event[iBef].p();
if (eGnow > eGspl) {
iGspl = i;
eGspl = eGnow;
}
}
}
if (iGspl == -1) return false;
// Split this gluon into a collinear quark.antiquark pair.
int iG = systemPtr->iParton[iGspl];
int idNewQ = flavSelPtr->pickLightQ();
int iNewQ = event.append( idNewQ, 101, iG, 0, 0, 0, event[iG].col(), 0,
0.5 * event[iG].p(), 0.5 * event[iG].m(), 0.);
int iNewQb = event.append( -idNewQ, 101, iG, 0, 0, 0, 0, event[iG].acol(),
0.5 * event[iG].p(), 0.5 * event[iG].m(), 0.);
event[iG].statusNeg();
event[iG].daughters( iNewQ, iNewQb);
// Order partons in new system. Note order of colour flow.
int iNext = iGspl + 1;
if (iNext == systemPtr->size()) iNext = 0;
if (event[ systemPtr->iParton[iNext]].acol() != event[iNewQ].col())
swap( iNewQ, iNewQb);
vector<int> iNewSys;
iNewSys.push_back( iNewQ);
for (int i = iGspl + 1; i < systemPtr->size(); ++i)
iNewSys.push_back( systemPtr->iParton[i]);
for (int i = 0; i < iGspl; ++i)
iNewSys.push_back( systemPtr->iParton[i]);
iNewSys.push_back( iNewQb);
// Erase the old system and insert the new one instead.
colConfig.erase(iSys);
colConfig.insert( iNewSys, event);
// Done.
return true;
}
//--------------------------------------------------------------------------
// Split a single colour singlet that contains two sparticles.
// To fix : if nLeg >= 3 && mMin large handle as in nLeg == 1??
bool RHadrons::splitSystem( ColConfig& colConfig, Event& event) {
// First and second R-hadron mother. Number of legs in between.
int iFirst = -1;
int iSecond = -1;
for (int i = 0; i < int(systemPtr->size()); ++i) {
int iTmp = systemPtr->iParton[i];
if ( givesRHadron( event[iTmp].id()) ) {
if (iFirst == -1) iFirst = i;
else iSecond = i;
}
}
int nLeg = iSecond - iFirst;
// New flavour pair for breaking the string, and its mass.
int idNewQ = flavSelPtr->pickLightQ();
double mNewQ = particleDataPtr->constituentMass( idNewQ);
vector<int> iNewSys1, iNewSys2;
// If sparticles are neighbours then need new q-qbar pair in between.
if (nLeg == 1) {
// The location of the two sparticles.
int i1Old = systemPtr->iParton[iFirst];
int i2Old = systemPtr->iParton[iSecond];
// Take a fraction of momentum to give breakup quark pair.
double mHat = (event[i1Old].p() + event[i2Old].p()).mCalc();
double mMax = mHat - event[i1Old].m() - event[i2Old].m();
if (mMax < 2. * (mNewQ + MSAFETY)) return false;
double mEff = min( 2. * (mNewQ + mOffsetCloudRH), mMax - 2. * MSAFETY);
double frac = mEff / mHat;
Vec4 pEff = frac * (event[i1Old].p() + event[i2Old].p());
// New kinematics by (1) go to same mHat with bigger masses, and
// (2) rescale back down to original masses and reduced mHat.
Vec4 p1New, p2New;
if ( !newKin( event[i1Old].p(), event[i2Old].p(),
event[i1Old].m() / (1. - frac), event[i2Old].m() / (1. - frac),
p1New, p2New) ) return false;
p1New *= 1. - frac;
p2New *= 1. - frac;
// Fill in new partons after branching, with correct colour/flavour sign.
int i1New, i2New, i3New, i4New;
int newCol = event.nextColTag();
i1New = event.copy( i1Old, 101);
if (event[i2Old].acol() == event[i1Old].col()) {
i3New = event.append( -idNewQ, 101, i1Old, 0, 0, 0,
0, event[i2Old].acol(), 0.5 * pEff, 0.5 * mEff, 0.);
i2New = event.copy( i2Old, 101);
event[i2New].acol( newCol);
i4New = event.append( idNewQ, 101, i2Old, 0, 0, 0,
newCol, 0, 0.5 * pEff, 0.5 * mEff, 0.);
} else {
i3New = event.append( idNewQ, 101, i1Old, 0, 0, 0,
event[i2Old].col(), 0, 0.5 * pEff, 0.5 * mEff, 0.);
i2New = event.copy( i2Old, 101);
event[i2New].col( newCol);
i4New = event.append( -idNewQ, 101, i2Old, 0, 0, 0,
0, newCol, 0.5 * pEff, 0.5 * mEff, 0.);
}
// Modify momenta and history. For iBotCopyId tracing asymmetric
// bookkeeping where one sparticle is radiator and the other recoiler.
event[i1New].p( p1New);
event[i2New].p( p2New);
event[i1Old].daughters( i1New, i3New);
event[i1New].mother2( 0);
event[i2Old].daughters( i2New, i4New);
event[i2New].mother2( 0);
iBefRHad[0] = i1New;
iBefRHad[1] = i2New;
// Partons in the two new systems.
for (int i = 0; i < iFirst; ++i)
iNewSys1.push_back( systemPtr->iParton[i]);
iNewSys1.push_back( i1New);
iNewSys1.push_back( i3New);
iNewSys2.push_back( i4New);
iNewSys2.push_back( i2New);
for (int i = iSecond + 1; i < int(systemPtr->size()); ++i)
iNewSys2.push_back( systemPtr->iParton[i]);
// If one gluon between sparticles then split it into a
// collinear q-qbar pair.
} else if (nLeg == 2) {
// Gluon to be split and its two daughters.
int iOld = systemPtr->iParton[iFirst + 1];
int i1New = event.append( idNewQ, 101, iOld, 0, 0, 0,
event[iOld].col(), 0, 0.5 * event[iOld].p(),
0.5 * event[iOld].m(), 0.);
int i2New = event.append( -idNewQ, 101, iOld, 0, 0, 0,
0, event[iOld].acol(), 0.5 * event[iOld].p(),
0.5 * event[iOld].m(), 0.);
event[iOld].statusNeg();
event[iOld].daughters( i1New, i2New);
// Partons in the two new systems.
if (event[systemPtr->iParton[iFirst]].col() == event[i2New].acol())
swap( i1New, i2New);
for (int i = 0; i <= iFirst; ++i)
iNewSys1.push_back( systemPtr->iParton[i]);
iNewSys1.push_back( i1New);
iNewSys2.push_back( i2New);
for (int i = iSecond; i < int(systemPtr->size()); ++i)
iNewSys2.push_back( systemPtr->iParton[i]);
// If several gluons between sparticles then find lowest-mass gluon pair
// and replace it by a q-qbar pair.
} else {
// Find lowest-mass gluon pair and adjust effective quark mass.
int iMin = 0;
int i1Old = 0;
int i2Old = 0;
double mMin = 1e20;
for (int i = iFirst + 1; i < iSecond - 1; ++i) {
int i1Tmp = systemPtr->iParton[i];
int i2Tmp = systemPtr->iParton[i + 1];
double mTmp = (event[i1Tmp].p() + event[i2Tmp].p()).mCalc();
if (mTmp < mMin) {
iMin = i;
i1Old = i1Tmp;
i2Old = i2Tmp;
mMin = mTmp;
}
}
double mEff = min( mNewQ + mOffsetCloudRH, 0.4 * mMin);
// New kinematics by sharing mHat appropriately.
Vec4 p1New, p2New;
if ( !newKin( event[i1Old].p(), event[i2Old].p(),
mEff, mEff, p1New, p2New, false) ) return false;
// Insert new partons and update history.
int i1New, i2New;
if (event[systemPtr->iParton[0]].acol() == 0) {
i1New = event.append( -idNewQ, 101, i1Old, 0, 0, 0,
0, event[i1Old].acol(), p1New, mEff, 0.);
i2New = event.append( idNewQ, 101, i2Old, 0, 0, 0,
event[i2Old].col(), 0, p2New, mEff, 0.);
} else {
i1New = event.append( idNewQ, 101, i1Old, 0, 0, 0,
event[i1Old].col(), 0, p1New, mEff, 0.);
i2New = event.append( -idNewQ, 101, i2Old, 0, 0, 0,
0, event[i2Old].acol(), p2New, mEff, 0.);
}
event[i1Old].statusNeg();
event[i2Old].statusNeg();
event[i1Old].daughters( i1New, 0);
event[i2Old].daughters( i2New, 0);
// Partons in the two new systems.
for (int i = 0; i < iMin; ++i)
iNewSys1.push_back( systemPtr->iParton[i]);
iNewSys1.push_back( i1New);
iNewSys2.push_back( i2New);
for (int i = iMin + 2; i < int(systemPtr->size()); ++i)
iNewSys2.push_back( systemPtr->iParton[i]);
}
// Erase the old system and insert the two new ones instead.
colConfig.erase(iSys);
colConfig.insert( iNewSys1, event);
colConfig.insert( iNewSys2, event);
// Done.
return true;
}
//--------------------------------------------------------------------------
// Produce a R-hadron from a squark and another string end.
bool RHadrons::produceSquark( ColConfig& colConfig, Event& event) {
// Initial values.
int nBody = 0;
int iRNow = 0;
int iNewQ = 0;
int iNewL = 0;
// Check at which end of the string the squark is located.
int idAbsTop = event[ systemPtr->iParton[0] ].idAbs();
bool sqAtTop = (allowRSb && idAbsTop == idRSb)
|| (allowRSt && idAbsTop == idRSt);
// Copy down system consecutively from squark end.
int iBeg = event.size();
iCreRHad[iRHad] = iBeg;
if (sqAtTop) for (int i = 0; i < systemPtr->size(); ++i)
event.copy( systemPtr->iParton[i], 102);
else for (int i = systemPtr->size() - 1; i >= 0; --i)
event.copy( systemPtr->iParton[i], 102);
int iEnd = event.size() - 1;
// Input flavours. From now on H = heavy and L = light string ends.
int idOldH = event[iBeg].id();
int idOldL = event[iEnd].id();
// Pick new flavour to form R-hadron.
FlavContainer flavOld( idOldH%10);
int idNewQ = flavSelPtr->pick(flavOld).id;
int idRHad = toIdWithSquark( idOldH, idNewQ);
if (idRHad == 0) {
infoPtr->errorMsg("Error in RHadrons::produceSquark: "
"cannot form R-hadron code");
return false;
}
// Target mass of R-hadron and z value of fragmentation function.
double mRHad = particleDataPtr->m0(idRHad) + event[iBeg].m()
- ( (abs(idOldH) == idRSb) ? m0Sb : m0St );
double z = zSelPtr->zFrag( idOldH, idNewQ, mRHad*mRHad);
// Basic kinematics of string piece where break is to occur.
Vec4 pOldH = event[iBeg].p();
int iOldL = iBeg + 1;
Vec4 pOldL = event[iOldL].p();
double mOldL = event[iOldL].m();
double mNewH = mRHad / z;
double sSys = (pOldH + pOldL).m2Calc();
double sRem = (1. - z) * (sSys - mNewH*mNewH);
double sMin = pow2(mOldL + mCollapseRH);
// If too low remaining mass in system then add one more parton to it.
while ( ( sRem < sMin || sSys < pow2(mNewH + mOldL + MSAFETY) )
&& iOldL < iEnd ) {
++iOldL;
pOldL += event[iOldL].p();
mOldL = event[iOldL].m();
sSys = (pOldH + pOldL).m2Calc();
sRem = (1. - z) * (sSys - mNewH*mNewH);
sMin = pow2(mOldL + mCollapseRH);
}
// If enough mass then split off R-hadron and reduced system.
if ( sRem > sMin && sSys > pow2(mNewH + mOldL + MSAFETY) ) {
Vec4 pNewH, pNewL;
if ( !newKin( pOldH, pOldL, mNewH, mOldL, pNewH, pNewL) ) {
infoPtr->errorMsg("Error in RHadrons::produceSquark: "
"failed to construct kinematics with reduced system");
return false;
}
// Insert R-hadron with new momentum.
iRNow = event.append( idRHad, 104, iBeg, iOldL, 0, 0, 0, 0,
z * pNewH, mRHad, 0.);
// Reduced system with new string endpoint and modified recoiler.
idNewQ = -idNewQ;
bool hasCol = (idNewQ > 0 && idNewQ < 10) || idNewQ < -10;
int col = (hasCol) ? event[iOldL].acol() : 0;
int acol = (hasCol) ? 0 : event[iOldL].col();
iNewQ = event.append( idNewQ, 105, iBeg, iOldL, 0, 0, col, acol,
(1. - z) * pNewH, (1. - z) * mNewH, 0.);
iNewL = event.copy( iOldL, 105);
event[iNewL].mothers( iBeg, iOldL);
event[iNewL].p( pNewL);
// Done with processing of split to R-hadron and reduced system.
nBody = 3;
}
// Two-body final state: form light hadron from endpoint and new flavour.
if (nBody == 0) {
FlavContainer flav1( idOldL);
FlavContainer flav2( -idNewQ);
int iTry = 0;
int idNewL = flavSelPtr->combine( flav1, flav2);
while (++iTry < NTRYMAX && idNewL == 0)
idNewL = flavSelPtr->combine( flav1, flav2);
if (idNewL == 0) {
infoPtr->errorMsg("Error in RHadrons::produceSquark: "
"cannot form light hadron code");
return false;
}
double mNewL = particleDataPtr->mass( idNewL);
// Check that energy enough for light hadron and R-hadron.
if ( sSys > pow2(mRHad + mNewL + MSAFETY) ) {
Vec4 pRHad, pNewL;
if ( !newKin( pOldH, pOldL, mRHad, mNewL, pRHad, pNewL) ) {
infoPtr->errorMsg("Error in RHadrons::produceSquark: "
"failed to construct kinematics for two-hadron decay");
return false;
}
// Insert R-hadron and light hadron.
iRNow = event.append( idRHad, 104, iBeg, iOldL, 0, 0, 0, 0,
pRHad, mRHad, 0.);
event.append( idNewL, 105, iBeg, iOldL, 0, 0, 0, 0,
pNewL, mNewL, 0.);
// Done for two-body case.
nBody = 2;
}
}
// Final case: for very low mass collapse to one single R-hadron.
if (nBody == 0) {
idRHad = toIdWithSquark( idOldH, idOldL);
if (idRHad == 0) {
infoPtr->errorMsg("Error in RHadrons::produceSquark: "
"cannot form R-hadron code");
return false;
}
// Insert R-hadron with new momentum.
iRNow = event.append( idRHad, 104, iBeg, iOldL, 0, 0, 0, 0,
systemPtr->pSum, systemPtr->mass, 0.);
// Done with one-body case.
nBody = 1;
}
// History bookkeeping: the R-hadron and processed partons.
iRHadron[iRHad] = iRNow;
int iLast = event.size() - 1;
for (int i = iBeg; i <= iOldL; ++i) {
event[i].statusNeg();
event[i].daughters( iRNow, iLast);
}
// Remove old string system and, if needed, insert a new one.
colConfig.erase(iSys);
if (nBody == 3) {
vector<int> iNewSys;
iNewSys.push_back( iNewQ);
iNewSys.push_back( iNewL);
for ( int i = iOldL + 1; i <= iEnd; ++i) iNewSys.push_back( i);
colConfig.insert( iNewSys, event);
}
// Copy lifetime and vertex from sparticle to R-hadron.
event[iRNow].tau( event[iBef].tau() );
if (event[iBef].hasVertex()) event[iRNow].vProd( event[iBef].vProd() );
// Done with production of a R-hadron from a squark.
return true;
}
//--------------------------------------------------------------------------
// Produce a R-hadron from a gluino and two string ends (or a gluon).
bool RHadrons::produceGluino( ColConfig& colConfig, Event& event) {
// Initial values.
int iGlui = 0;
int idSave = 0;
int idQLeap = 0;
bool isDiq1 = false;
vector<int> iSide1, iSide2, iSideTmp, iNewSys1, iNewSys2;
Vec4 pGlui, pSide1, pSide2;
// Decide whether to produce a gluinoball or not.
bool isGBall = (rndmPtr->flat() < probGluinoballRH);
// Extract one string system on either side of the gluino.
for (int i = 0; i < systemPtr->size(); ++i) {
int iTmp = systemPtr->iParton[i];
if (iGlui == 0 && event[ iTmp ].id() == idRGo) {
iGlui = iTmp;
pGlui = event[ iTmp ].p();
} else if (iGlui == 0) {
iSideTmp.push_back( iTmp);
pSide1 += event[ iTmp ].p();
} else {
iSide2.push_back( iTmp);
pSide2 += event[ iTmp ].p();
}
}
// Order sides from gluino outwards and with lowest relative mass first.
for (int i = int(iSideTmp.size()) - 1; i >= 0; --i)
iSide1.push_back( iSideTmp[i]);
double m1H = (pGlui + pSide1).mCalc() - event[ iSide1.back() ].m();
double m2H = (pGlui + pSide2).mCalc() - event[ iSide2.back() ].m();
if (m2H < m1H) {
swap( iSide1, iSide2);
swap( pSide1, pSide2);
}
// Begin loop over two sides of gluino, with lowest relative mass first.
for (int iSide = 1; iSide < 3; ++iSide) {
// Begin processing of lower-mass string side.
int idRHad = 0;
double mRHad = 0.;
int nBody = 0;
int iRNow = 0;
int iNewQ = 0;
int iNewL = 0;
int statusRHad = 0;
// Copy down system consecutively from gluino end.
int iBeg = event.size();
if (iSide == 1) {
iCreRHad[iRHad] = iBeg;
event.copy( iGlui, 102);
for (int i = 0; i < int(iSide1.size()); ++i)
event.copy( iSide1[i], 102);
} else {
event.copy( iGlui, 102);
for (int i = 0; i < int(iSide2.size()); ++i)
event.copy( iSide2[i], 102);
}
int iEnd = event.size() - 1;
// Pick new flavour to help form R-hadron. Initial colour values.
int idOldL = event[iEnd].id();
int idNewQ = 21;
if (!isGBall) {
do {
FlavContainer flavOld( idOldL);
idNewQ = -flavSelPtr->pick(flavOld).id;
} while (iSide == 2 && isDiq1 && abs(idNewQ) > 10);
if (iSide == 1) isDiq1 = (abs(idNewQ) > 10);
}
bool hasCol = (event[iEnd].col() > 0);
int colR = 0;
int acolR = 0;
// Target intermediary mass or R-hadron mass.
if (iSide == 1) {
idSave = idNewQ;
idRHad = (hasCol) ? 1009002 : -1009002;
if (hasCol) colR = event[iBeg].col();
else acolR = event[iBeg].acol();
statusRHad = 103;
double mNewQ = particleDataPtr->constituentMass( idNewQ);
if (isGBall) mNewQ *= 0.5;
mRHad = event[iBeg].m() + mOffsetCloudRH + mNewQ;
} else {
idRHad = toIdWithGluino( idSave, idNewQ);
if (idRHad == 0) {
infoPtr->errorMsg("Error in RHadrons::produceGluino: "
"cannot form R-hadron code");
return false;
}
statusRHad = 104;
mRHad = particleDataPtr->m0(idRHad) + event[iBeg].m() - m0Go;
}
// z value of fragmentation function.
double z = zSelPtr->zFrag( idRGo, idNewQ, mRHad*mRHad);
// Basic kinematics of string piece where break is to occur.
Vec4 pOldH = event[iBeg].p();
int iOldL = iBeg + 1;
Vec4 pOldL = event[iOldL].p();
double mOldL = event[iOldL].m();
double mNewH = mRHad / z;
double sSys = (pOldH + pOldL).m2Calc();
double sRem = (1. - z) * (sSys - mNewH*mNewH);
double sMin = pow2(mOldL + mCollapseRH);
// If too low remaining mass in system then add one more parton to it.
while ( ( sRem < sMin || sSys < pow2(mNewH + mOldL + MSAFETY) )
&& iOldL < iEnd ) {
++iOldL;
pOldL += event[iOldL].p();
mOldL = event[iOldL].m();
sSys = (pOldH + pOldL).m2Calc();
sRem = (1. - z) * (sSys - mNewH*mNewH);
sMin = pow2(mOldL + mCollapseRH);
}
// If enough mass then split off R-hadron and reduced system.
if ( sRem > sMin && sSys > pow2(mNewH + mOldL + MSAFETY) ) {
Vec4 pNewH, pNewL;
if ( !newKin( pOldH, pOldL, mNewH, mOldL, pNewH, pNewL) ) {
infoPtr->errorMsg("Error in RHadrons::produceGluino: "
"failed to construct kinematics with reduced system");
return false;
}
// Insert intermediary or R-hadron with new momentum, less colour.
iRNow = event.append( idRHad, statusRHad, iBeg, iOldL,
0, 0, colR, acolR, z * pNewH, mRHad, 0.);
// Reduced system with new string endpoint and modified recoiler.
if (!isGBall) idNewQ = -idNewQ;
int colN = (hasCol) ? 0 : event[iOldL].acol();
int acolN = (hasCol) ? event[iOldL].col() : 0;
iNewQ = event.append( idNewQ, 105, iBeg, iOldL, 0, 0,
colN, acolN, (1. - z) * pNewH, (1. - z) * mNewH, 0.);
iNewL = event.copy( iOldL, 105);
event[iNewL].mothers( iBeg, iOldL);
event[iNewL].p( pNewL);
// Collect partons of new string system.
if (iSide == 1) {
iNewSys1.push_back( iNewQ);
iNewSys1.push_back( iNewL);
for ( int i = iOldL + 1; i <= iEnd; ++i) iNewSys1.push_back( i);
} else {
iNewSys2.push_back( iNewQ);
iNewSys2.push_back( iNewL);
for ( int i = iOldL + 1; i <= iEnd; ++i) iNewSys2.push_back( i);
}
// Done with processing of split to R-hadron and reduced system.
nBody = 3;
}
// For side-1 low-mass glueball system reabsorb full momentum.
if (nBody == 0 && isGBall && iSide == 1) {
idQLeap = event[iOldL].id();
Vec4 pNewH = event[iBeg].p() + pOldL;
// Insert intermediary R-hadron with new momentum, less colour.
iRNow = event.append( idRHad, statusRHad, iBeg, iEnd,
0, 0, colR, acolR, pNewH, pNewH.mCalc(), 0.);
nBody = 1;
}
// Two-body final state: form light hadron from endpoint and new flavour.
// Also for side 2 if gluinoball formation gives quark from side 1.
if (nBody == 0 && (!isGBall || (iSide == 2 && idQLeap != 0) )) {
if (isGBall) idNewQ = -idQLeap;
FlavContainer flav1( idOldL);
FlavContainer flav2( -idNewQ);
int iTry = 0;
int idNewL = flavSelPtr->combine( flav1, flav2);
while (++iTry < NTRYMAX && idNewL == 0)
idNewL = flavSelPtr->combine( flav1, flav2);
if (idNewL == 0) {
infoPtr->errorMsg("Error in RHadrons::produceGluino: "
"cannot form light hadron code");
return false;
}
double mNewL = particleDataPtr->mass( idNewL);
// Check that energy enough for light hadron and R-hadron.
if ( sSys > pow2(mRHad + mNewL + MSAFETY) ) {
Vec4 pRHad, pNewL;
if ( !newKin( pOldH, pOldL, mRHad, mNewL, pRHad, pNewL) ) {
infoPtr->errorMsg("Error in RHadrons::produceGluino: "
"failed to construct kinematics for two-hadron decay");
return false;
}
// Insert intermediary or R-hadron and light hadron.
iRNow = event.append( idRHad, statusRHad, iBeg, iOldL, 0, 0,
colR, acolR, pRHad, mRHad, 0.);
event.append( idNewL, 105, iBeg, iOldL, 0, 0, 0, 0,
pNewL, mNewL, 0.);
// Done for two-body case.
nBody = 2;
// For this case gluinoball should be handled as normal flavour.
isGBall = false;
}
}
// Final case: for very low mass collapse to one single R-hadron.
if (nBody == 0 && (!isGBall || (iSide == 2 && idQLeap != 0) )) {
if (isGBall) idSave = idQLeap;
if (iSide == 1) idSave = idOldL;
else idRHad = toIdWithGluino( idSave, idOldL);
if (idRHad == 0) {
infoPtr->errorMsg("Error in RHadrons::produceGluino: "
"cannot form R-hadron code");
return false;
}
// Insert R-hadron with new momentum.
iRNow = event.append( idRHad, statusRHad, iBeg, iOldL, 0, 0,
colR, acolR, pOldH + pOldL, (pOldH + pOldL).mCalc(), 0.);
// Done with one-body case.
// Even if hoped-for, it was not possible to create a gluinoball.
isGBall = false;
}
// History bookkeeping: the processed partons.
int iLast = event.size() - 1;
for (int i = iBeg; i <= iOldL; ++i) {
event[i].statusNeg();
event[i].daughters( iRNow, iLast);
}
// End of loop over two sides of the gluino.
iGlui = iRNow;
}
// History bookkeeping: insert R-hadron; delete old string system.
if (iGlui == 0) {
infoPtr->errorMsg("Error in RHadrons::produceGluino: "
"could not handle gluinoball kinematics");
return false;
}
iRHadron[iRHad] = iGlui;
colConfig.erase(iSys);
// Non-gluinoball: insert (up to) two new string systems.
if (!isGBall) {
if (iNewSys1.size() > 0) colConfig.insert( iNewSys1, event);
if (iNewSys2.size() > 0) colConfig.insert( iNewSys2, event);
// Gluinoball with enough energy in first string:
// join two temporary gluons into one.
} else if (idQLeap == 0) {
int iG1 = iNewSys1[0];
int iG2 = iNewSys2[0];
int colG = event[iG1].col() + event[iG2].col();
int acolG = event[iG1].acol() + event[iG2].acol();
Vec4 pG = event[iG1].p() + event[iG2].p();
int iG12 = event.append( 21, 105, iG1, iG2, 0, 0, colG, acolG,
pG, pG.mCalc(), 0.);
// Temporary gluons no longer needed, but new colour to avoid warnings.
event[iG1].id( 21);
event[iG2].id( 21);
event[iG1].statusNeg();
event[iG2].statusNeg();
int colBridge = event.nextColTag();
if (event[iG1].col() == 0) {
event[iG1].col( colBridge);
event[iG2].acol( colBridge);
} else {
event[iG1].acol( colBridge);
event[iG2].col( colBridge);
}
// Form the remnant system from which the R-hadron has been split off.
vector<int> iNewSys12;
for (int i = int(iNewSys1.size()) - 1; i > 0; --i)
iNewSys12.push_back( iNewSys1[i]);
iNewSys12.push_back( iG12);
for (int i = 1; i < int(iNewSys2.size()); ++i)
iNewSys12.push_back( iNewSys2[i]);
colConfig.insert( iNewSys12, event);
// Gluinoball where side 1 was fully eaten, and its flavour content
// should leap over to the other side, to a gluon there.
} else {
int iG2 = iNewSys2[0];
event[iG2].id( idQLeap);
colConfig.insert( iNewSys2, event);
}
// Copy lifetime and vertex from sparticle to R-hadron.
event[iGlui].tau( event[iBef].tau() );
if (event[iBef].hasVertex()) event[iGlui].vProd( event[iBef].vProd() );
// Done with production of a R-hadron from a gluino.
return true;
}
//--------------------------------------------------------------------------
// Form a R-hadron code from a squark and a (di)quark code.
// First argument is the (anti)squark, second the (anti)(di)quark.
int RHadrons::toIdWithSquark( int id1, int id2) {
// Check that physical combination; return 0 if not.
int id1Abs = abs(id1);
int id2Abs = abs(id2);
if (id2Abs < 10 && id1 > 0 && id2 > 0) return 0;
if (id2Abs < 10 && id1 < 0 && id2 < 0) return 0;
if (id2Abs > 10 && id1 > 0 && id2 < 0) return 0;
if (id2Abs > 10 && id1 < 0 && id2 > 0) return 0;
// Form R-hadron code. Flip sign for antisquark.
bool isSt = (id1Abs == idRSt);
int idRHad = 1000000;
if (id2Abs < 10) idRHad += ((isSt) ? 600 : 500) + 10 * id2Abs + 2;
else idRHad += ((isSt) ? 6000 : 5000) + 10 * (id2Abs/100) + id2Abs%10;
if (id1 < 0) idRHad = -idRHad;
// Done.
return idRHad;
}
//--------------------------------------------------------------------------
// Resolve a R-hadron code into a squark and a (di)quark.
// Return a pair, where first is the squark and the second the (di)quark.
pair<int,int> RHadrons::fromIdWithSquark( int idRHad) {
// Find squark flavour content.
int idLight = (abs(idRHad) - 1000000) / 10;
int idSq = (idLight < 100) ? idLight/10 : idLight/100;
int id1 = (idSq == 6) ? idRSt : idRSb;
if (idRHad < 0) id1 = -id1;
// Find light (di)quark flavour content.
int id2 = (idLight < 100) ? idLight%10 : idLight%100;
if (id2 > 10) id2 = 100 * id2 + abs(idRHad)%10;
if ((id2 < 10 && idRHad > 0) || (id2 > 10 && idRHad < 0)) id2 = -id2;
// Done.
return make_pair( id1, id2);
}
//--------------------------------------------------------------------------
// Form a R-hadron code from two quark/diquark endpoints and a gluino.
int RHadrons::toIdWithGluino( int id1, int id2) {
// Check that physical combination; return 0 if not. Handle gluinoball.
int id1Abs = abs(id1);
int id2Abs = abs(id2);
if (id1Abs == 21 && id2Abs == 21) return 1000993;
int idMax = max( id1Abs, id2Abs);
int idMin = min( id1Abs, id2Abs);
if (idMin > 10) return 0;
if (idMax > 10 && id1 > 0 && id2 < 0) return 0;
if (idMax > 10 && id1 < 0 && id2 > 0) return 0;
if (idMax < 10 && id1 > 0 && id2 > 0) return 0;
if (idMax < 10 && id1 < 0 && id2 < 0) return 0;
// Form R-meson code. Flip sign for antiparticle.
int idRHad = 0;
if (idMax < 10) {
idRHad = 1009003 + 100 * idMax + 10 * idMin;
if (idMin != idMax && idMax%2 == 1) {
if (id1Abs == idMax && id1 > 0) idRHad = -idRHad;
if (id2Abs == idMax && id2 > 0) idRHad = -idRHad;
}
if (idMin != idMax && idMax%2 == 0) {
if (id1Abs == idMax && id1 < 0) idRHad = -idRHad;
if (id2Abs == idMax && id2 < 0) idRHad = -idRHad;
}
// Form R-baryon code. Flip sign for antiparticle.
} else {
int idA = idMax/1000;
int idB = (idMax/100)%10;
int idC = idMin;
if (idC > idB) swap( idB, idC);
if (idB > idA) swap( idA, idB);
if (idC > idB) swap( idB, idC);
idRHad = 1090004 + 1000 * idA + 100 * idB + 10 * idC;
if (id1 < 0) idRHad = -idRHad;
}
// Done.
return idRHad;
}
//--------------------------------------------------------------------------
// Resolve a R-hadron code into two quark/diquark endpoints (and a gluino).
// Return a pair, where first carries colour and second anticolour.
pair<int,int> RHadrons::fromIdWithGluino( int idRHad) {
// Find light flavour content of R-hadron.
int idLight = (abs(idRHad) - 1000000) / 10;
int id1, id2, idTmp, idA, idB, idC;
// Gluinoballs: split g into d dbar or u ubar.
if (idLight < 100) {
id1 = (rndmPtr->flat() < 0.5) ? 1 : 2;
id2 = -id1;
// Gluino-meson: split into q + qbar.
} else if (idLight < 1000) {
id1 = (idLight / 10) % 10;
id2 = -(idLight % 10);
// Flip signs when first quark of down-type.
if (id1%2 == 1) {
idTmp = id1;
id1 = -id2;
id2 = -idTmp;
}
// Gluino-baryon: split to q + qq (diquark).
// Pick diquark at random, except if c or b involved.
} else {
idA = (idLight / 100) % 10;
idB = (idLight / 10) % 10;
idC = idLight % 10;
double rndmQ = 3. * rndmPtr->flat();
if (idA > 3) rndmQ = 0.5;
if (rndmQ < 1.) {
id1 = idA;
id2 = 1000 * idB + 100 * idC + 3;
if (idB != idC && rndmPtr->flat() > diquarkSpin1RH) id2 -= 2;
} else if (rndmQ < 2.) {
id1 = idB;
id2 = 1000 * idA + 100 * idC + 3;
if (idA != idC && rndmPtr->flat() > diquarkSpin1RH) id2 -= 2;
} else {
id1 = idC;
id2 = 1000 * idA + 100 * idB +3;
if (idA != idB && rndmPtr->flat() > diquarkSpin1RH) id2 -= 2;
}
}
// Flip signs for anti-R-hadron.
if (idRHad < 0) {
idTmp = id1;
id1 = -id2;
id2 = -idTmp;
}
// Done.
return make_pair( id1, id2);
}
//--------------------------------------------------------------------------
// Construct modified four-vectors to match modified masses:
// minimal reshuffling of momentum along common axis.
// Note that last two arguments are used to provide output!
bool RHadrons::newKin( Vec4 pOld1, Vec4 pOld2, double mNew1, double mNew2,
Vec4& pNew1, Vec4& pNew2, bool checkMargin) {
// Squared masses in initial and final kinematics.
double sSum = (pOld1 + pOld2).m2Calc();
double sOld1 = pOld1.m2Calc();
double sOld2 = pOld2.m2Calc();
double sNew1 = mNew1 * mNew1;
double sNew2 = mNew2 * mNew2;
// Check that kinematically possible.
if (checkMargin && pow2(mNew1 + mNew2 + MSAFETY) > sSum) return false;
// Transfer coefficients to give four-vectors with the new masses.
double lamOld = sqrt( pow2(sSum - sOld1 - sOld2) - 4. * sOld1 * sOld2 );
double lamNew = sqrt( pow2(sSum - sNew1 - sNew2) - 4. * sNew1 * sNew2 );
double move1 = (lamNew * (sSum - sOld1 + sOld2)
- lamOld * (sSum - sNew1 + sNew2)) / (2. * sSum * lamOld);
double move2 = (lamNew * (sSum + sOld1 - sOld2)
- lamOld * (sSum + sNew1 - sNew2)) / (2. * sSum * lamOld);
// Construct final vectors. Done.
pNew1 = (1. + move1) * pOld1 - move2 * pOld2;
pNew2 = (1. + move2) * pOld2 - move1 * pOld1;
return true;
}
//==========================================================================
} // end namespace Pythia8
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