Rivet analyses

title: BELLE_2010_I899499

Photon Energy and Hadronic mass spectrum in $B\to X_s\ell^+\ell^-$

Experiment: BELLE (KEKB)

Inspire ID: 899499

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - PoS ICHEP2010 (2010) 231

Beams: * *

Beam energies: ANY

Run details: none listed

Measurement of the photon energy and hadronic mass spectrum in $B\to X_s\ell^+\ell^-$. This conference proceding is more recent than the publication in BELLE_2005_I679052, however the data had to be read from the figures.

Source code:BELLE_2010_I899499.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B -> Xs l+ l- class BELLE_2010_I899499 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2010_I899499);


/// @name Analysis methods
/// @{

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(UnstableParticles(Cuts::abspid == 521 || Cuts::abspid == 511), "UFS");
  // histos
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h[ix], 1, 1, 1 + ix);
  }
  book(_c, "TMP/Nb");
}

void findDecayProducts(bool& charm,
                       const Particle& mother,
                       unsigned int& nK0,
                       unsigned int& nKp,
                       unsigned int& nKm,
                       Particles& lp,
                       Particles& lm) {
  for (const Particle& p : mother.children()) {
    int id = p.pid();
    if (PID::isCharmHadron(p.pid()))
      charm = true;
    else if (id == PID::POSITRON || id == PID::ANTIMUON)
      lp.push_back(p);
    else if (id == PID::ELECTRON || id == PID::MUON)
      lm.push_back(p);
    else if (id == PID::KPLUS)
      ++nKp;
    else if (id == PID::KMINUS)
      ++nKm;
    else if (id == PID::K0S)
      ++nK0;
    else if (id == PID::PI0 || id == PID::PIPLUS || id == PID::PIMINUS) {
      continue;
    }
    else if (!p.children().empty()) {
      findDecayProducts(charm, p, nK0, nKp, nKm, lp, lm);
    }
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  // Loop over bottoms
  for (const Particle& bottom : apply<UnstableParticles>(event, "UFS").particles()) {
    // remove mixing entries etc
    if (bottom.children()[0].abspid() == bottom.abspid()) continue;
    _c->fill();
    bool charm = false;
    Particles lp, lm;
    unsigned int nK0(0), nKp(0), nKm(0);
    findDecayProducts(charm, bottom, nK0, nKp, nKm, lp, lm);
    if (charm) continue;
    unsigned int nk = nKp - nKm + nK0;
    if (nk % 2 == 0) continue;
    if (lp.size() != 1 || lm.size() != 1 || lp[0].pid() != -lm[0].pid()) continue;
    FourMomentum qq = lp[0].mom() + lm[0].mom();
    double q2 = qq.mass2();
    if (q2 < 0.04) continue;
    _h[0]->fill((bottom.mom() - qq).mass());
    _h[1]->fill(q2);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h, 0.5e6 / *_c);
}

/// @}


/// @name Histograms
/// @{
CounterPtr _c;
Histo1DPtr _h[2];
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2010_I899499);

} ```