Rivet analyses

title: CMS_2011_I883318

$B^+$ cross section at 7 TeV

Experiment: CMS (LHC)

Inspire ID: 883318

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 106 (2011) 112001 - arXiv: 1101.0131 - Expt page: CMS-BPH-10-004

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - bottom meson production

Measurement of the cross section for the production of $B^+$ mesons at 7 TeV by the CMS experiment.

Source code:CMS_2011_I883318.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B+ at 7 TeV class CMS_2011_I883318 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2011_I883318);


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

/// Book histograms and initialise projections before the run
void init() {
  // projection
  declare(UnstableParticles(), "UFS");
  // histograms
  book(_h_total, 1, 1, 1);
  book(_h_pT, 2, 1, 1);
  book(_h_y, 3, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  if (_edges[0].empty()) {
    _edges[0] = _h_total->xEdges();
    _edges[1] = _h_pT->xEdges();
  }
  // Final state of unstable particles to get particle spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  // loop over B+ states
  for (const Particle& p : ufs.particles(Cuts::abspid == 521)) {
    // cuts on pT and rapidity
    const double y = p.absrap();
    const double pT = p.perp();
    if (pT < 5. || y > 2.4) continue;
    _h_total->fill(_edges[0][0]);
    const size_t idx = _axis.index(pT);
    const string edge = (idx && idx < _edges[1].size()) ? _edges[1][idx - 1] : "OTHER"s;
    _h_pT->fill(edge);
    _h_y->fill(y);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double fact = 0.5 * crossSection() / microbarn / sumOfWeights();
  scale(_h_total, fact);
  scale(_h_pT, fact);
  for (auto& b : _h_pT->bins()) {
    const size_t idx = b.index();
    b.scaleW(1.0 / _axis.width(idx));
  }
  // 0.5 from +/- y
  scale(_h_y, 0.5 * fact);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _h_total, _h_pT;
Histo1DPtr _h_y;
vector<string> _edges[2];
YODA::Axis<double> _axis{5.0, 10.0, 13.0, 17.0, 24.0, 30.0};
/// @}

};

RIVET_DECLARE_PLUGIN(CMS_2011_I883318);

} ```