Rivet analyses

title: LHCB_2012_I1184177

Fraction of $\Upsilon(1S)$ from $\chi_b(1P)$ decays at 7 TeV

Experiment: LHCB (LHC)

Inspire ID: 1184177

Status: VALIDATED

Authors: - Peter Richardson

References: - JHEP 11 (2012) 031

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - chi_b(1P) and upsilon(1S) production

Measurement of the fraction of $\Upsilon(1S)$ from $\chi_b(1P)$ decays at 7 TeV

Source code:LHCB_2012_I1184177.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief chi_b(1p) production at 7 TeV class LHCB_2012_I1184177 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2012_I1184177);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(), "UFS");
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h_pT[ix], "TMP/pT_" + toString(ix), refData(1, 1, 1));
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  // Final state of unstable particles to get particle spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

  for (const Particle& p :
       ufs.particles(Cuts::pid == 553 || Cuts::pid == 10551 || Cuts::pid == 20553 || Cuts::pid == 555)) {
    // J/psi as a reference
    if (p.pid() == 553) {
      double absrap = p.absrap();
      if (absrap > 2. && absrap < 4.5) _h_pT[1]->fill(p.perp());
    }
    else {
      Particle Upsilon;
      if (p.children()[0].pid() == 22 && p.children()[1].pid() == 553) {
        Upsilon = p.children()[1];
      }
      else if (p.children()[1].pid() == 22 && p.children()[0].pid() == 553) {
        Upsilon = p.children()[0];
      }
      else
        continue;
      double absrap = Upsilon.absrap();
      if (absrap < 2. || absrap > 4.5) continue;
      _h_pT[0]->fill(Upsilon.perp());
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // compute fraction
  Estimate1DPtr tmp;
  book(tmp, 1, 1, 1);
  efficiency(_h_pT[0], _h_pT[1], tmp);
  tmp->scale(100.);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_pT[2];
/// @}

};

RIVET_DECLARE_PLUGIN(LHCB_2012_I1184177);

} ```