Rivet analyses

title: LHCB_2019_I1716259

Rate of $\Xi_b^-$ production at 7, 8 and 13 TeV

Experiment: LHCB (LHC)

Inspire ID: 1716259

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 99 (2019) 5, 052006

Beams: p+ p+

Beam energies: (3500.0, 3500.0); (4000.0, 4000.0); (6500.0, 6500.0)GeV

Run details: - Xib production

Measurement of the rate of $\Xi_b^-$ production relative to that for $\Lambda_b^0$ production at 7, 8, and 13 TeV by the LHCb experiment.

Source code:LHCB_2019_I1716259.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Xi_b- 7,8 and 13 TeV class LHCB_2019_I1716259 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2019_I1716259);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(UnstableParticles(), "UFS");
  // CMS energy
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    if (isCompatibleWithSqrtS(eVal)) {
      _sqs = (en == "13000"s) ? "13"s : "7 & 8"s;
    }
  }
  raiseBeamErrorIf(_sqs.empty());

  // histograms
  for (const string& en : vector<string>{"7 & 8"s, "13"s}) {
    for (size_t ix = 0; ix < 2; ++ix) {
      book(_c[en + "xi" + toString(ix)], "TMP/c_xi_" + toString(ix + 1) + "_" + en);
      book(_c[en + "lam" + toString(ix)], "TMP/c_lam_" + toString(ix + 1) + "_" + en);
    }
  }
  const auto& ref = refData<YODA::BinnedEstimate<string>>(1, 1, 1);
  book(_h_xi, "TMP/h_xi", ref);
  book(_h_lam, "TMP/h_lam", ref);
}

void findDecayProducts(const Particle& mother,
                       double sign,
                       Particles& Lambda,
                       Particles& Xi,
                       Particles& Jpsi,
                       unsigned int& nstable) const {
  for (const Particle& p : mother.children()) {
    if (p.pid() == 3122 * sign)
      Lambda += p;
    else if (p.pid() == 3312 * sign)
      Xi += p;
    else if (p.pid() == 443)
      Jpsi += p;
    else if (p.pid() == 111 || p.children().empty())
      ++nstable;
    else
      findDecayProducts(p, sign, Lambda, Xi, Jpsi, nstable);
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == 5122 || Cuts::abspid == 5132)) {
    // decay modes
    Particles Lambda, Xi, Jpsi;
    unsigned int nstable = 0;
    double sign = p.pid() > 0 ? 1. : -1.;
    findDecayProducts(p, sign, Lambda, Xi, Jpsi, nstable);
    if (p.abspid() == 5112) {
      _c[_sqs + "lam1"s]->fill();
      if (Lambda.size() == 1 && Jpsi.size() == 1 && nstable == 0) _c[_sqs + "lam0"s]->fill();
    }
    else {
      _c[_sqs + "xi1"]->fill();
      if (Xi.size() == 1 && Jpsi.size() == 1 && nstable == 0) _c[_sqs + "xi0"]->fill();
    }
    // pT and rapidity cuts
    if (p.pT() > 20 * GeV) continue;
    const double eta = p.abseta();
    if (eta < 2. || eta > 6.) continue;
    if (p.abspid() == 5122) {
      _h_lam->fill(_sqs);
    }
    else {
      _h_xi->fill(_sqs);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // first the simple ratio
  BinnedEstimatePtr<string> tmp;
  book(tmp, 2, 1, 1);
  divide(_h_xi, _h_lam, tmp);
  // and the one with brs included
  book(tmp, 1, 1, 1);
  for (const auto& b : tmp->bins()) {
    const string edge = b.xEdge();
    if (_c[edge + "xi1"]->sumW() > 0) {
      _h_xi->bin(b.index()).scaleW(dbl(*_c[edge + "xi0"] / *_c[edge + "xi1"]));
    }
    if (_c[edge + "lam1"]->sumW() > 0) {
      _h_lam->bin(b.index()).scaleW(dbl(*_c[edge + "lam0"] / *_c[edge + "lam1"]));
    }
  }
  divide(_h_xi, _h_lam, tmp);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _h_xi, _h_lam;
map<string, CounterPtr> _c;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(LHCB_2019_I1716259);

} ```