Rivet analyses

title: LHCB_2016_I1391317

$\Lambda_b^0$ and $B^0$ production at 7 and 8 TeV

Experiment: LHCB (LHC)

Inspire ID: 1391317

Status: VALIDATED

Authors: - Peter Richardson

References: - Chin.Phys.C 40 (2016) 011001, 2016

Beams: p+ p+

Beam energies: (3500.0, 3500.0); (4000.0, 4000.0)GeV

Run details: - hadronic events

Double differential cross section in $p_\perp$ and $y$ for $\Lambda_b^0$ and $B^0$ production at 7 and 8 TeV.

Source code:LHCB_2016_I1391317.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Lambda_b and B0 production at 7 and 8 TeV class LHCB_2016_I1391317 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2016_I1391317);


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

/// Book histograms and initialise projections before the run
void init() {

  declare(UnstableParticles(), "UFS");

  for (double eVal : allowedEnergies()) {
    const int en = round(eVal);
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;

    int ih(en == 8000);
    // histograms
    book(_h_Lambda[en], {2.0, 2.5, 3.0, 3.5, 4.0, 4.5});
    book(_h_B[en], {2.0, 2.5, 3.0, 3.5, 4.0, 4.5});
    for (size_t iy = 0; iy < _h_Lambda[en]->numBins(); ++iy) {
      book(_h_Lambda[en]->bin(iy + 1), 1 + ih, 1, 1 + iy);
      book(_h_B[en]->bin(iy + 1), 3 + ih, 1, 1 + iy);
    }
    for (size_t ix = 0; ix < 2; ++ix) {
      book(_h_pT[en + ix], "TMP/h_pT_" + toString(en + ix), refData(5, 1, 1 + ih));
      book(_h_y[en + ix], "TMP/h_y_" + toString(en + ix), refData(6, 1, 1 + ih));
    }
  }
  raiseBeamErrorIf(_sqs == 0);
}


/// 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");
  // loop over onium states
  for (const Particle& p : ufs.particles(Cuts::abspid == 5122 || Cuts::abspid == 511)) {
    // skip copies due mixing
    if (p.children().size() == 1 && p.children()[0].abspid() == p.abspid()) continue;
    const double rap = p.rap();
    if (rap < 2. || rap > 4.5) continue;
    const double pT = p.pT();
    if (p.abspid() == 5122) {
      _h_Lambda[_sqs]->fill(rap, pT / GeV);
      if (p.pid() > 0) {
        _h_pT[_sqs + 0]->fill(pT / GeV);
        if (pT < 20 * GeV) _h_y[_sqs + 0]->fill(rap);
      }
      else {
        _h_pT[_sqs + 1]->fill(pT);
        if (pT < 20 * GeV) _h_y[_sqs + 1]->fill(rap);
      }
    }
    else {
      _h_B[_sqs]->fill(rap, pT / GeV);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // branching ratios
  const vector<double> br = {3.2e-4, 1.27e-3};
  // 0.5 particle/antiparticle
  const double factor = 0.5 * crossSection() / picobarn / sumOfWeights();

  scale(_h_Lambda, br[0] * factor);
  divByGroupWidth(_h_Lambda);
  scale(_h_B, br[1] * factor);
  divByGroupWidth(_h_B);

  for (double eVal : allowedEnergies()) {
    const int en = int(eVal + 0.5);
    int ih(en == 8000);
    Estimate1DPtr tmp;
    book(tmp, 5, 1, 1 + ih);
    asymm(_h_pT[en + 0], _h_pT[en + 1], tmp);
    tmp->scale(100.);
    book(tmp, 6, 1, 1 + ih);
    asymm(_h_y[en + 0], _h_y[en + 1], tmp);
    tmp->scale(100.);
  }
}

/// @}


/// @name Histograms
/// @{
map<int, Histo1DGroupPtr> _h_Lambda, _h_B;
map<int, Histo1DPtr> _h_pT, _h_y;
int _sqs = 0;
/// @}

};

RIVET_DECLARE_PLUGIN(LHCB_2016_I1391317);

} ```