void Boost_To_Stop_Rest_Frame(TLorentzVector& stop4, TLorentzVector& chargino4, TLorentzVector& b4, TLorentzVector& neutralino4, TLorentzVector& W4, TLorentzVector& up4, TLorentzVector& down4, TLorentzVector& s4)
{
TVector3 betaV(-stop4.Px()/stop4.Energy(),-stop4.Py()/stop4.Energy(),-stop4.Pz()/stop4.Energy());
stop4.Boost(betaV);
chargino4.Boost(betaV);
b4.Boost(betaV);
neutralino4.Boost(betaV);
W4.Boost(betaV);
up4.Boost(betaV);
down4.Boost(betaV);
s4.SetE(chargino4.P()/chargino4.M());
s4.SetVect(chargino4.Vect().Unit()*chargino4.Gamma());
}
double KinUtils::doElasticRecoil(const TLorentzVector &chi, TLorentzVector &recoil, TLorentzVector &recoil_chi, const int &procID) {
TVector3 v0, v1, v2;
TVector3 p0, pr, pchi;
double E0, Er, Echi;
double Tr_max; //this is the maximum recoil KINETIC energy for this incoming chi
double P0, Pr, Pchi;
double ctheta_r, stheta_r, phi_r, sigma;
int ii;
E0 = chi.E();
P0 = chi.P();
p0 = chi.Vect();
/*1: extract the recoil total energy from the cross-section*/
ii = 0;
ii = (int) (E0 / (Ebeam / nFunctionsElastic));
if (ii >= nFunctionsElastic) ii = nFunctionsElastic - 1; //should not happen!!!
if (procID == Proc_Pelastic) {
Tr_max = (2 * Mn * (E0 * E0 - Mchi * Mchi)) / (2 * E0 * Mn + Mn * Mn + Mchi * Mchi); //maximum energy transfer
if (Tr_max < (Pthr + Pbinding)) return 0; //this event is not compatible with the threshold, it is useless to proceed further
} else if (procID == Proc_Eelastic) {
Tr_max = (2 * Me * (E0 * E0 - Mchi * Mchi)) / (2 * E0 * Me + Me * Me + Mchi * Mchi); //maximum energy transfer
if (Tr_max < Ethr) {
//cout<<"THR IS: "<<Ethr<<" "<<Tr_max<<" "<<E0<<endl;
return 0; //this event is not compatible with the threshold, it is useless to proceed further
}
} else if (procID == Proc_Nuclelastic) {
Tr_max = (2 * Mnucl * (E0 * E0 - Mchi * Mchi)) / (2 * E0 * Mnucl + Mnucl * Mnucl + Mchi * Mchi); //maximum energy transfer
if (Tr_max < Nuclthr) {
//cout<<"THR IS: "<<Ethr<<" "<<Tr_max<<" "<<E0<<endl;
return 0; //this event is not compatible with the threshold, it is useless to proceed further
}
}
if (procID == Proc_Pelastic) {
Er = f_chipXsection[ii]->GetRandom(Pthr + Pbinding + Mn, Tr_max + Mn);
} else if (procID == Proc_Eelastic) {
Er = f_chieXsection[ii]->GetRandom(Ethr + Me, Tr_max + Me);
} else if (procID == Proc_Nuclelastic) {
Er = f_chinuclXsection[ii]->GetRandom(Nuclthr, Tr_max); //Here the variable is the KINETIC energy of the recoiling nucleus
Er = Er + Mnucl;
}
/*1a: correct the proton energy for binding effects*/
if (procID == Proc_Pelastic) {
Er = Er - Pbinding; /*Effective binding energy correction*/
}
/*1b: compute x-section total . No time consuming, since integrals are cached!*/
if (procID == Proc_Pelastic) {
sigma = f_chipXsection[ii]->Integral(Pthr + Pbinding + Mn, Tr_max + Mn);
} else if (procID == Proc_Eelastic) {
sigma = f_chieXsection[ii]->Integral(Ethr + Me, Tr_max + Me);
} else if (procID == Proc_Nuclelastic) {
sigma = f_chinuclXsection[ii]->Integral(Nuclthr, Tr_max); //Has to be integrated in this range since the variable is the KINETIC energy here (and not the total as before)
}
/*2: compute recoil chi TOTAL energy*/
if (procID == Proc_Pelastic) {
Echi = E0 + Mn - Er;
} else if (procID == Proc_Eelastic) {
Echi = E0 + Me - Er;
} else if (procID == Proc_Nuclelastic) {
Echi = E0 + Mnucl - Er;
}
/*3: compute the momenta*/
Pchi = sqrt(Echi * Echi - Mchi * Mchi);
if (procID == Proc_Pelastic) {
Pr = sqrt(Er * Er - Mn * Mn);
} else if (procID == Proc_Eelastic) {
Pr = sqrt(Er * Er - Me * Me);
} else if (procID == Proc_Nuclelastic) {
Pr = sqrt(Er * Er - Mnucl * Mnucl);
}
/*4: compute the angle of the recoil nucleon wrt the initial chi momentum direction*/
if (procID == Proc_Pelastic) {
ctheta_r = E0 * E0 - Echi * Echi + Er * Er - Mn * Mn;
ctheta_r /= 2 * P0 * Pr;
} else if (procID == Proc_Eelastic) {
ctheta_r = E0 * E0 - Echi * Echi + Er * Er - Me * Me;
ctheta_r /= 2 * P0 * Pr;
} else if (procID == Proc_Nuclelastic) {
ctheta_r = E0 * E0 - Echi * Echi + Er * Er - Mnucl * Mnucl;
ctheta_r /= 2 * P0 * Pr;
}
if (ctheta_r > 1) ctheta_r = 1;
if (ctheta_r < -1) ctheta_r = -1;
stheta_r = sqrt(1 - ctheta_r * ctheta_r);
/*5: The azimuthal angle (around the incoming chi momentum direction) is flat*/
phi_r = Rand.Uniform(-PI, PI);
/*6: Now set the 4-vectors*/
/*6a: build an orthogonal coordinate system, with v0 along the initial chi momentum direction*/
v0 = chi.Vect().Unit();
v1 = v0.Orthogonal();
v1 = v1.Unit();
v2 = v0.Cross(v1); //v2 = v0 x v1
/*write the 3-momenta*/
pr = v0 * Pr * ctheta_r + v1 * Pr * stheta_r * sin(phi_r) + v2 * Pr * stheta_r * cos(phi_r);
pchi = p0 - pr;
/*6b:Set them */
recoil.SetVect(pr);
recoil.SetE(Er);
recoil_chi.SetVect(pchi);
recoil_chi.SetE(Echi);
return sigma;
}