// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief B_s0 -> D_s* semileptonic decay
class LHCB_2020_I1787090 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2020_I1787090);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(UnstableParticles(), "UFS");
// Book histograms
book(_h_w , 1, 1, 1);
}
// Calculate the Q2 using mother and daugher meson
double w(const Particle& B, int mesonID) {
Particle D = filter_select(B.children(), Cuts::pid==mesonID)[0];
FourMomentum q = B.mom() -D.mom() ;
double q2 = q*q;
return 0.5*(sqr(B.mass())+sqr(D.mass())-q2)/B.mass()/D.mass();
}
// Check for explicit decay into pdgids
bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
// Trivial check to ignore any other decays but the one in question modulo photons
const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
if (children.size()!=ids.size()) return false;
// Check for the explicit decay
return all(ids, [&](int i){return count(children, hasPID(i))==1;});
}
/// Perform the per-event analysis
void analyze(const Event& event) {
for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==531)) {
if(p.pid()<0) {
if(isSemileptonicDecay(p, {433, PID::MUON, PID::NU_MUBAR})) {
_h_w->fill(w(p, 433));
}
}
else {
if(isSemileptonicDecay(p, {-433, PID::ANTIMUON, PID::NU_MU})) {
_h_w->fill(w(p, -433));
}
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
// normalize to unity
normalize(_h_w);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_w;
/// @}
};
RIVET_DECLARE_PLUGIN(LHCB_2020_I1787090);
}